apply for and obtain letters of administration from district court if mother died intestate
2) enclose copy of mother death certificate
3) it should not take more than 6 months
4) then apply to society to transfer mother one third share in flat in your name
5) in the alternative if your mother had left any nomination form apply to society to transfer mother one third share of flat in your name
6) society would transfer flat in your name on execution of indemnity bond