Right of remarried sister-in-law in mother-in-laws property

Actually the things is That my mother was working in a MCD Primary school.. Unfortunately she was expired before retirement.. and the gpf nomination has my name and my big brother name.. and i have one big sister , she is married and working in Govt school as a teachern my brother also expired on 2012 ... and my brother was married and his wife and his 5 year son{My nephew} went from my home after the death of my brother ans also we get the news that she got married in her town but she didnt tell us.. now she come back and asking the share in my mother GPF and retirment funds... n also in 2007 my mother disowned my big brother and published in newspaper.... so i would like to ask that my sister in law has any right in my mother retirement funds.... n my sister in law is not living with us since my brother expired.. Please advice me what i can do. Thanks and Regards.