Adultery is no longer an offence 

2) it was consensual sex and no offence has been committed by the lady

3) merely on basis of call records no case is made out 

Adultary is not an offence now after supreme court order in this regard.

So nobody can take any legal action. Similarly police can not take any action from its own.

Adultery is not punishable if it is consensual between two adults how ever the police may take efforts if the family matter may be sorted out. Otherwise the wife have the remedy to go for divorce and file maintenance petition. The husband may not be arrested for adultery.

No immortal activities case is not maintainable now. Even adultery cannot be filed. 

- Supreme court declared that , when  a man and a woman in love live together , is part of the right to life and not a criminal offence, and further live-in relationships is legal in India.

- Z or police cannot take any legal action against X as per law.

- X should lodge a complaint with the police and higher official , that Z is trying to black mailing & threatening her for life .

- Further, if Y is not cooperating then , X should lodge her complaint against him on the ground of longtime relationship. 

- Further, the Protection of Women from Domestic Violence Act 2005 provides for the protection, maintenance and right of palimony to a live-in partner, if she complains.

The police has no rights to file any case against your friend X  especially when this is not at all an offence.

If Y had relationship with X then it is personal to which even court cannot interfere.

The latest supreme court judgment is very clear on this that 

In a landmark judgement today, the Supreme Court scrapped the 150-year old adultery law. ... "Adultery cannot and should not be a crime. It can be a ground for a civil offence, a ground for divorce," a five judge bench led by outgoing Chief Justice of India Dipak Misra said.

Now SC has just remove adultery as crime and shown a open minded thought and said relations physical or emotional are completely subject to an individual thoughts no law can control or comment on that

So your friend need not be worried about that, she can ask the police to proceed, but the police may file false cases on different provisions of law which may trouble her.

1. No case can be filed against X For having extra marital affair with Y under adultery as this section have been repealed by Supreme Court.

2. A complaint against SHO can be send to SP for illegal confisticating the phone of X and harassing her. 

3. Z cannot lodge any complaint against X under any section because they don't have any direct contact with each other.

4. Case of immoral activities cannot be registered for any conversation between two adults.

adultery is not a criminal offence. police cannot take any action against your friend. 

See SHO Cannot apply any section against them both since the adultery is scrapped also even there was law on same in this situation his wife can only seek divorce cannot file any criminal action against them.

1. Action taken by SHO is illegal. Section 497 IPC which earlier criminalised adultery has been struck down as unconstitutional by the Supreme Court.

2. This is no immoral activity. The maximum which Z can do is file a petition for divorce on the ground of adultery against Y.

3. If X and Y are harassed by police then they may file a petition in the High Court to seek protection.

Dear Sir,

India’s supreme court strikes down a colonial-era adultery law

Extramarital sex is not a criminal offence in India anymore.

A man can only be prosecuted for the offence of adultery only when, the aggrieved husband makes a complaint in court. Procedure regulating criminal law says, a court cannot take matter relating to adultery unless the “aggrieved” husband makes a complaint. Making it more simpler, here is a detailed step-wise functioning of law on adultery in India.

Wife can’t file complaint against hubby’s ‘keep’ under IPC: RTI

NAGPUR: Even as the Centre has opposed a plea in Supreme Court that seeks to make men and women equally liable for adultery, an RTI reply revealed about gender discrimination in the Indian Penal Code, particularly against wife, under Section 497 (adultery) of the IPC.
The reply by Ministry of Home Affairs informed that there is no other law besides this IPC section for registering offences under the term ‘adultery’. It means, only a husband can file a criminal case under Section 497 against the paramour with whom his wife had undergone a sexual intercourse. However, a wife cannot lodge a complaint against the woman with whom her husband has physical relationship.

The central government had recently filed an affidavit in the Supreme Court strongly advocating that adultery should remain an offence. It also opposed a plea seeking to make men and women equally liable under Section 497. The affidavit was filed in response to a case where apex court’s constitutional bench is re-examining the constitutionality of Section 497 that incorporates provisions for the adultery law. The SC bench would examine whether exemption granted to women from adultery needs a change.
The RTI was filed by Dr Indrajit Khandekar, professor and in-charge of Clinical Forensic Medicine Unit (CFMU) at Mahatma Gandhi Institute of Medical Sciences (MGIMS). He stated that there was clear discrimination in the laws as a married man can file criminal case under adultery against his wife’s paramour, but a wife can’t.
“In ultimate analysis, our Indian laws unfortunately endorses that the wife is the husband’s property and conveys that a man is entitled to have exclusive possession and access to his wife’s sexuality. Moreover, a woman is not eligible to have such an exclusive right and claim over her husband. She is, therefore, not entitled to prosecute either her promiscuous husband or the ‘outsider woman’ with whom her husband had consensual sex,” he said.
In his RTI query, Khandekar had asked whether there is any section in IPC which permits the wife to file a criminal case against the other woman with whom the husband had indulged in physical contact without wife’s consent.
What Section 497 of IPC says
Adultery — Whoever has sexual intercourse with a person who is and whom he knows or has reason to believe to be the wife of another man, without the consent or connivance of that man, such intercourse not amounting to the offence of rape, is guilty of the offence of adultery, and shall be punished with imprisonment of either description for a term which may extend to five years, or with fine, or with both. In such case the wife shall not be punishable as an abettor.

No criminal case made out, SHO acted illegally. Complain to women cell and area SP. SHO will suspend. Having external affair not a crime. And she could have easily ignored his summon. Every thing is doe without authority.

Complain to news paper. Phone cannot be confiscate.