Do my mother will get her rights?

My father MADAN BASFOR married to my mother REKHA BASFOR in Jan 1990 ,again my father was forced to marry to a women named SONAMUKHI BASFOR in Oct 1990 because she was pregnant and blamed my father for this shameless action . In 1992 SONAMUKHI field a maintainance case against my father and won the case by the order of which my father paid Rs.300 -2200 to her upto Sept 2016.To get rid of this my father filled a Divorce case against Sonamukhi basfor in 2014 and before the judgement my father died. My father was a centrail govt. employ and gave his nomaniee to my mother’s name including me and my sister. Now my father died on 22 Sept 2016 But the actual problem is ,since we have a name in my fathers service file nomaniee after claiming for the death benafith we came to know that Sonamukhi Basfor also want the other benafith and give a hand written application to the office mambers and asked them to stop the benafith in favour of us. So we want any of the best lawyer fo fight the case for us and before that give us the legal suggestion in this complicated case. Please help. The marriage with SONAMUKHI BASFOR was a social marriage and with my mother a social marriage with a panchayat letter as a proof. WHAT TO DO PLS HELP.