Right to husband property

Hello Sir,

My sister and her husband were living separately because of his husband was oppressed her everyday and also was beating her. But 3 month ago her husband dead due to corona at his hometown , Dhule, Maharashtra. Now my sister want to take his husband House and want to live there which is in Dhule but homes key is having at husband's sister and those peoples now denied to handover the keys. So please guide us what action should we take now.
Please guide us.

Thanks and regards
Varun