Legal Heirship Certificate - Query.

What about your mother? 

What is the urgency now?  If the legal heir certificate states only your name as sole legal heir, then there may not be any necessity for such SC.  Only if there is a fear of challenge of title in future, then there may be a problem.  If there are no Class 1 legal heirs, then you are sole legal heir and contact a local advocate to convince yourself.

[1] Since the nomination is in the name of the son, the society will have to transfer the share certificate to the name of the nominee, [2] You will have to obtain a succession certificate from the Hon.Bombay High Court to become the absolute owner of the flat.

Nomination is in your name. It was given by your Father in whose name the Share Certificate is Father and Mother already deceased. So what is the immediate need and necessity for the Succession Certificate or Legal Heir Certificate. You may apply to the Society along with your Aadhar Card (as identity proof for you where your father's name also appears), Death Certificate of your father, and Death Certificate of your Mother if need be. Impress upon them to transfer the Share Certificate in terms of Nomination already in their records.

[1] It is specified, in the Model Bye-Laws of Co-Operative Housing Society of Maharashtra, that society is legally obliged to transfer the share certificate of the flat to the nomiee. [2] Nomiee does not become the absolute owner of the flat neither has he the voting power in the society, [3] In order to become the absolute owner of the flat the legal beneficiary of the owner has to get a succession certificate from the Hon. Bombay High Court.