Mother's property transfer to son

My grnd fathr n fathr died w/o making WILL. So me, brothr, sistr n buaji make a reliqueshment deed in my mothers favour.my mother sold that residential property n buy new house on her name.ow mymother wants to transfer that property on our name...please tell me how?so my married sister can't ask for her share n mother also can't challenge in future and we get property right away...someone told me that the WILL can be challenge...i m hindu....