Railway pension for widow daughter

I am a widow daughter of a past employee (Late Jyotish Chandra Banerjee) of railways.My mother (Late Suniti Banerjee) got pension after my fathers death (20-Dec-1990) and being ignorant and lack of proper resources I did not know that I am also eligible for pension after my mothers death since my husband expired on 17-Oct-1987 before my mother was still alive. My mother expired on 18-Mar-1994. Someone told me that I can claim even now since its been many years of my mothers death. My livelihood had been very difficult since then just because of being ignorant and no support I did not claimed earlier. Unfortunately I lost all the documents of my parents few years back in a fire. It would be really great if you could guide how can I make it and whom should I approach. As I am not getting any kind of cooperation from Indian Rail and State Bank Of India (Last pension drawn from this bank on Feb-1994) since 2011 I started trying. My Fathers Bank Details : Bank Name:State Bank Of India Branch Name:BELILIOUS ROAD Address:158/3,BELILIOUS ROAD,P.O. KADAMTALA DT HOWRAH , W B HOWRAH City:HOWRAH District:HOWRAH State:West Bengal Micr Code:700002116 IFSC Code:SBIN0003412 Job Description Of My Father : My Father was a Tool Checker at Bamangachi Lokomotive.