1) apply for mutation of property in your mother name
2) enclose father death certificate
3) gift deed or relinquishment deed by other legal heirs
4) if no objections are received property would be mutated in mother name
5) your mother can also apply for letters of administration from court
6) consent affidavit can be executed by other legal heirs to relinquish their interest in father property
7) court would in case no ob case is received from any legal heir issue letters of administration in your mother name