Someone should review the facts and options with an attorney on your daughter's behalf.
Banks often send regular statements. Someone should review the father's incoming and already received mail to see what kind of statements he gets. Some banks offer the option of getting paperless statements. The father's emails likely should be reviewed also.
After a certain period of inactivity in an account, the bank likely is required by state law to send the balance to the state to hold in trust for the account holder or his heirs. The inactivity time varies by state and is usually several years.
The National Association of Unclaimed Property Administrators is a group of governments including many US states and Canadian provinces. It has a database to help locate unclaimed funds. Searching and claiming the unclaimed funds are free through the NAUPA. Its site is http://www.unclaimed.org/ . Proofs of identity are required to claim the funds.
Besides the bank account, there likely other financial issues that may involve the daughter. An attorney should be consulted to find out if anything can be done for the daughter.