Wife should apply for and obtain letters of administration from district court as husband died intestate 

2) enclose death certificate of deceased husband 

3) schedule of property 

4) succession certificate or legal heirs certificate would not suffice 

Heirship certificate is not suffice not to get ownership of flat 

The property was in the name of the deceased husband.

By transferring the society's share certificate o the wife's name, she will not become the absolute owner of the entire proeprty.

The property left behind by the deceased upon his intestate death shall devolve on all his legal heirs.

Thus the legal heirs have to give NOC to the society to transfer the share certificate in the name of the widow of the deceased owner, simultaneously they may have to execute a registered release deed relinquishing their rights n the property.

After this the wife of the deceased can apply for transfer of revenue records to her name from her deceased husband's name. 

Before that, they may have to obtain a legal heirship certificate from the revenue department to establish the names of the legal heirs of the deceased. 

Besides obtaining legal heirship certificate, the other legal heirs have o give their NOC to the society for transferring the share certificate to the wife of the deceased and also the other legal heirs have to execute a registered release deed relinquishing their rights in the property. 

1. You have not mentioned who else are there as the legal heirs of the said deceased husband. 

2. Collect legal heir certificate from your ward counselor of Salt Lake Municipal Corporation. He might ask for an affidavit from you affirming the name/s of the legal heirs.

3. Once the widow of the deceased person gets the legal heir certificate stating the she is the sole surviving lergal heir of  her late husband, a fresh certificate will be issued by the Society in her favour cancelling the share certificate which was originally issued in favour of her husband, since deceased. 

For claiming share/ownership of immoveable properties, legal heir certificate is enough.

1. Is wife the sole surviving Class 1 heir of this man?

2. Class 1 heirs of a Hindu male dying intestate are his mother, widow and children. If he is survived by children as well then they too have succeeded to the property along with mother.

3. All class 1 heirs have to execute the sale deed in favour of buyer unless one or some of them have relinquished his/their share.

If she obtains legal heirship/succession certificate with declatation that she is like successor of her husband, she can get the  title of the flat transferred to her name.