How to claim physical shares with only folio number.

So, have a friend whose father passed away recently two months back. The family has some shares in Lakshmi Finance & Industrial Corporation Limited held on her father's name whose dividend is being credited to her father's bank account. The family does not have access to the original Share Certificate, but know only "folio number" and have some printed letter of communication between Lakshmi Finance and their father. The letter had mention to something called IEPF (dont know what it is) if that might help you understand. How can these shares be claimed by her mother / her? I do not have any idea about there, maybe someone here can show the way?