What if my father died in United States. What if he had has six figures in USA membership rewards and I wanted to transfer them to one of his wife's frequent flyer/guest programs before the account is closed and I had online access

It seems as if there are no good bonus offers right now like BA, Delta, and no more Continental etc. Any suggestions before Amex would close the account. I am pretty sure amex uses the Social Security Death index to close accounts but no idea how much time I would have.