Husband died intestate.property transferred to wife after noc from children.can it be gifted to son?

If the son and daughters had relinquished their rights through a relinquishment deed, then the mother can handle the property as though it is her own. There are High Court judgments that there is no stamp duty based on the value of property relinquished. There will be a nominal stamp duty.

Transfer in Societies record alone is no transfer in Mumbai even if NOC was obtained from other heirs. Society cannot determine who are the heirs and who are not. Society can transfer under Sec:30. But it will not be a conclusive transfer. The person to whom transferred will be only a "provisional member" without beneficial rights. If the deceased person had made a will, the will should be probated by competent authority and the property distributed. If there was no will, succession certificate should be obtained from appropriate court. If the wife holds the property without any claim being made by anyone else for 12 years, then it becomes hers under the Limitation Act and she can transfer it to anyone as she would wish to.

No Relenquishment Deed was executed. Affadavit was made & Notarized to with a request to transfer the Ownership rights of the Flat to the Wife of the deceased by the Daughters & Son. With this the Society transferred the Flat in the name of the Wife & the Share Certificate was also transferred.

Can it be transferred to the Son by Will or by Gift Deed?

Is the NOC of the daughters required?

The questions here are:

1. Whether an NOC by an heir can be considered on par with a relinquishment of rights. Whether the heir or his/her surviving descendant can refute the NOC and stake a claim in due course. 

2. Whether there are any other heir or heirs, who have not given NOC and who can stake a claim later.

I am not aware of any law or judgment which  answer the above questions. The best thing that the lady, in whose name the flat is now can do is, she can give a public notice in two prominent newspapers stating that she proposes to transfer her rights on capital and property of the Society to her son and that anyone having objections to it should give them to her or the Society in writing within a stipulated time. If no objections are received she can transfer the property to her son paying stamp duty and registering the same. She can then submit the documents to the Society to enter her son's name.