Under Section 12(1)(a) of the Hindu Marriage Act, 1955, a marriage is voidable and can be annulled if it remains unconsummated due to the respondent's impotency. Furthermore, under the principle of fraudulent misrepresentation, hiding such a condition at the time of marriage is a legally recognized form of mental cruelty. 

2)you can  seek alimony from husband .the husband claim that he spent lot of money on marriage and hence should be paid out of girl jewellery is not maintainable 

3) Section 316 of BNS / Section 406 of IPC): Retaining her Stridhan, college certificates, and individual bank locker keys against her will is a criminal offense. The family can file an FIR or a private criminal complaint. : If convicted, the perpetrators can face imprisonment for up to 3 years, a fine, or both

Since you have already approached court for solution including divorce as well as return of her articles and also maintenance amount, you may have to follow it up scrupulously. 

Under Indian law, she has significant remedies to recover her belongings and hold them accountable for the fraud and cruelty.

The husband has no legal right to withhold her jewelry, bank keys, or college certificates. In India, a woman's Stridhan (gifts, jewelry, and property given to her before, during, or after marriage) belongs exclusively to her.

Section 14 of the Hindu Succession Act / Civil Suit: Affirms her absolute ownership over her Stridhan.

Retaining her Stridhan and vital legal/educational documents against her will constitutes a criminal offense. Filing a police complaint or an application before the court under section Section 316 of the Bharatiya Nyaya Sanhita / BNS for the immediate release of her certificates and jewelry is highly effective.

The behavior described hiding a major physical condition, isolating her, putting her under surveillance, forcing her to sleep separately, and locking her out of the house amounts to intense mental and emotional cruelty.

She can file a case under the DV Act to claim multiple urgent reliefs (under Domestic Violence Act (PWDVA, 2005) for Residence Orders to secure access to her personal belongings and locker keys, for Monetary Relief / Maintenance for her daily sustenance and legal expenses and for Compensation towards specific  damages for the emotional torture and mental agony she endured.

Given that the husband has been dragging out court-appointed mediation for a year without genuine intent, your legal counsel should consider the following strategy she may inform the court or the mediator that the husband is using the platform as a stalling tactic and refusing to cooperate in good faith. Request the court to close mediation and move the matter to active litigation, request the court to direct the husband to immediately deposit her college certificates and locker keys into the custody of the court, prepare a list of all her items including stridhan and submit it before court for relief and remedy. 

On the facts stated, the wife may have both civil and criminal remedies. If impotence or inability to consummate the marriage was knowingly concealed before marriage, she may explore proceedings for annulment of marriage on the ground of fraud or material concealment, subject to the evidence available. The retention of her jewellery, certificates, bank-locker key, and other belongings may constitute unlawful withholding of her Stridhan, for which she can seek recovery through criminal proceedings and appropriate relief under the Protection of Women from Domestic Violence Act, 2005. In the DV case, she may seek return of Stridhan, compensation for mental cruelty, residence-related reliefs, and monetary reliefs. If an FIR has already been lodged, she should provide a detailed inventory of all retained articles and supporting documents. The husband cannot legally insist on deducting alleged wedding expenses from her jewellery. If mediation has failed despite repeated assurances, she may request the court to proceed with adjudication and seek appropriate interim and final reliefs, including maintenance or permanent alimony, depending upon the parties' financial circumstances and the evidence produced.