legal ownership of joint demat account

"A" and "B" are husband and wife and have two sons "C" and "D" "A" had a joint demat account with his wife "B". "A" dies without leaving a will. The contents of the demat account are transmitted by the bank to "B". "C" claims that under the Hindu Succession Act, he is a legal heir and is entitled to 1/3rd of the demat account contents. Question: What is the legal right of "C" 1) 0% - Since B is the Joint Holder. 2) 1/3rd - Since C is the legal heir. 3) 1/6th - Since B was always the absolute owner of 1/2 of the contents of the demat accounts, only "A" portion will be split between the legal heirs.