How to proceed with gift deed/senior citizen act

I have a flat in mumbai where it was jointly owned by father and mother. Now as my father has passed away without making a nominee and a will as of such 50% is co-owner my mother and rest 50% divided my 3 of us including my brother. His shared was already paid through another flat by my mother but has denied any payment as such, however, u have bank statement as evidence supporting the same. For which he unwilling to relinquish his deed and neither support my mother who is a senior citizen. He and his wife has harrassed and abused my mother and now sending legal notice for his share. Can I proceed to revoke his rights on other properties in mumbai & goa through senior citizen act? As she is a patient and has put false allegation of having medical support. Also, my mother wishes to transfer this flat in mumbai as a gift deed to me since I have looking after her medical and all other basic support for 12 years but unable to proceed without relinquishment deed of this. Would appreciate your advise in this matter. Thanks.