Define dormant account. What precautions would you take in dealing with a dormant account?

There is a savings bank account at your branch in the name of Mr. Nazmul Karim and Mrs. Khaleda Karim payable to either or survivor. The account has remained dormant since 2015. In January 2022, Mr. Shamsul Karim aged 22 years, claiming to be the only son of Mr. Nazmul Karim approaches you and informs as follows :

(i) He holds a statement of this account.
(ii) His mother Khaleda Karim died in 2012.
(iii) His father has left the house is 2010 and in missing since then.
(iv) He has the information that a safe deposit locker also there in their name. The key of the locker is not traceable.

He requests you to make payment of the balance in the account to him and also to deliver the contents lying in the locker to him. How would you deal with the case?