Property ownership transfer to mother after father death how to do it

My father died without will, leaving behind my mother, married sister(she has given up her claim for my mother on stamp paper attested by notary and judge), me my wife and my minor son. Now we want to transfer ownership in my mother's name. The property is society owned and with patta of society. There is no claim on property other than regular electricity and water bills. How should we proceed with transfer in shortest period of time?