The authorities within whose jurisdiction your brother's place of residence lies would issue such a certificate.

My brother passed away due to covid in India recently (late April 2021). My sister in law and my brother were visiting a smaller town in West Bengal (Durgapur) from Hyderabad when this happened. My sister in law needs to get a legal heir certificate now - does she need to get one from Durgapur (the place of her husband's death) or can she apply for one In Hyderabad (after she returns to Hyderabad). Any help or suggestion here would be appreciated ?