Settlement Deed

We are a family of 2 Sisters & a Son. One of my Parents property has 4 portions equally shared by my father & mother. In the past the entire property Power of Attorney was given on my name by both of my parents as my sister’s were given share in other properties. I work abroad & as my parents were growing old both of my sister’s managed to convince my parents & cancelled the Power of Attorney which was in my name. After that a settlement deed got executed on their names by my Parents. I was not kept informed about the same. Recently my father expired, but my mom is still alive & when I came for my father’s demise I learnt about the settlement deed by my mother. She wants to revoke her share of the settlement deed and keep the property till her death for her livelihood as my sister’s are not taking care of her as the settlement deed is executed and there is no love & loss with her any more. Request you all learned Friends to advise if there is any way out for her to cancel her part of Settlement Deed. Can I along with her approach the court as I’m a legal heir.