Does a son have any right over property of mother after giving up rights 20 years before her death?

A mother 'A' from muslim family had 2 children, 'B' a son with bad past with mother and 'C' a daughter who she used to live with until C's marriage. also note that A's husband had already divorced her and had a second marriage somewhere else. 20 years ago from now (then 2000) son B had a huge dispute and was violent with mother A, after other family member's interference son B agreed to sign an agreement stating him giving up his rights over mother's property and she can do as she will. in return to then 10,000 rupees in exchange. after which he disappears from mother A and daughter C's lives. skip to 20 years from then 2020 mother being a teacher from government school had built herself a big house(self acquired property) and willingly placed some amount in the names of daughter C and her 3 children. mother A passed away in 2019 without a written will. now the son B returns and since the house was left unattended (A used to live alone after marriage of C with C and her kids frequent visits during each vacations) B broke in the house and is now claiming rights over mother's property, is this allowed after the written document? on questioning now denies of signing any agreement in the first place? son B has made an affidavit for being a "heir" and just that on his side. while mother A didn't have a written will it was pretty obvious the son was cut off from inheritance. also can it be used as a will that mother A had daughter C and her 2 kids as nominee for her bank accounts?