Question for Bank of the Philippine Islands (BPI) - Dasmarinas, Cavite (E. Aguinaldo Highway)

For how long does an account of a deceased depositor stays in the bank? Can it still be withdraw if ten years dormant? What would the bank do let's say in 10 years time it isn't withdrawn? I need answer on this because I have a relative with a bank account in BPI. She died a long time ago. She has a 4million pesos deposited. Tnx