A Rep Payee has had a stroke. Her daughter wants to get information on the account that the Rep Payee on acting for her husband. What should the next step be?

The bank has no next steps. The family can contact Social Security to ask how they can have a new rep payee appointed in the event the current rep payee cannot fulfill their duties.

https://www.ssa.gov/payee/

IThere really isn't much you can do without exposing yourself to huge privacy risks. At the very least, seek legal counsel.

Related question about a rep payee account.....If the beneficiary owes the bank money from another closed account, can we exercise right of offset on the rep payee account?

Social Security and SSI funds are protected from any right of offset unless the account itself is overdrawn and a new deposit comes in.