Ask for a legal heir certificate not succession certificate.

Ensure all legal heirs to the property have given consent for sale.  The must sign the sale deed or give POA in this regard to execute the sale deed by their agents. 

1. See for mother share the son and father are legal heirs and for same letter of administration from court and mutation in there name is required.

Mutation records shall be required for the sale deed.

2. See if mutation is done then you can avoid succession dan can directly go for sale.

Only In most of the cases they ask succession certificate. But death certificate and affidavit for the same is enough

Insist on succession certificate 

2) mother share in flat should be transferred in name of legal heirs

3) then only sale deed should be executed by sellers

4) also insist on NOC from society

5) no dues certificate  

1.  Obtain a registered "release deed" from all the residual legal heirs of the deceased person.

2.  Based on the release deed, you can sell the property without having to conduct any court procedures.  At the most all the residual legal heirs can be made to sign the Sale Deed as "confirming & consenting parties", alongwith with you.

After the death of mother, the respective share will be distributed among the spouse, sons & daughters. mother share should be transferred to legal heirs. legal heir should execute sale deed. . 

After her death, her share inherited in him and father. Both can jointly sell the property, no document require except self declaration i.e. only legal heirs of deceased. 

SC dose not issue for immovable peropty but for shares, securities, bank money etc.

Wait till the son obtains the Succession Letter or certificate from the competent civil court. Thereafter proceed to register the property in your name, at the time of registration, obtain the signature of the Father/husband as the Consenting witness in your sale deed, to be executed by the son.

In fact the son could have obtained a Pouthi Katha after the death of his mother, as he was the joint co-owner of the property. He should have applied for the same enclosing a NOC letter from the father and a family tree to the BBMP office. It was much simpler. After submitting the same, the katha could have been transferred to the name of the son and then the son could have sold the property to you, with the father signing as the consenting or confirming party.

Now that the son has approached the civil court, it is better to wait and get the Succession Certificate from the court and then proceed as stated above.

Dear

The seller don't need succession certificate for transfer of share of mother instead the legal heir certificate from tehsildar is required for transfer of mother share on name of legal heirs that is son and her husband.

After obtaining legal heir certificate apply for mutation record updation. After this procedure sale can be done by consent of all legal heirs.

The property was jointly owned by mother and the son.

Upon the intestate death of the mother, her share in the property shall devolve equally on her own legal heirs consisting her husband and children.

A family tree certificate duly notarised shall be sufficient to proceed with the execution of the registered sale deed to be executed jointly by all the shareholders.

Succession certificate is not required for transactions pertaining to immovable property.

Hence you can safely ignore the requirement of succession certificate.

For other aspects you may please obtain a proper legal opinion about the proeprty and proceed only if recommended.

For movable property like the provident fund, bank deposits, shares, loans, or other securities, the succession certificate is required. For immovable property like land or jewellery, one has to produce the letter of administration in support of his or her claim

No succession certificate is not required for movable property letter of administration is required. Read Schedule VII of Indian Succession Act, 1925.

For immovable property you need letters of administration and not succession certificate 

2) A reading of Sections 370 and 372 of the Act, particularly, Clause (f) of Sub-section (1) of Section 372 of the Act, will show that a succession certificate can be applied for only in respect of debts and securities. The expression "Debt" has not been defined under the Act. The said expression has not been defined under the General Clauses Act as well. If so, one has to go by the ordinary meaning of the said expression. A debt means any pecuniary liability whether payable in presenti or in future to another in return for money, services, goods or any other obligation . A debt is also property in the form of a chose in action and is heritable and assignable as understood in law. In the case of securities Sub-section 2 of Section 370 of the Act enumerates the various securities envisaged by the section. They are as under:

(a) any promissory note, debenture, stock or other security of the Central Government or of a State Government;

(b) any bond, debenture, or annuity charged by Act of Parliament (of the United Kingdom) on the revenues of India;

(c) any stock or debenture of, or share in, a company or other incorporated institution:

(d) any debenture or other security for money issued by, or on behalf of, a local authority;

(e) any other security which the (State Government) may, by notification in the Official Gazette, declare to be a security for the purposes of this Part.

Yes it's required. Section 370 of Indian succession Act 1925

No, neither issued for Immovable property.

Succession certificate is not applicable for immovable property.