Can my dad sue the assisted living facility where my mom died & he still does not have his refund after 4 mths.

The facility and their home office; the people we need to talk to now don't answer my calls nor return my msgs. They sent a check a couple of mths ago made out to "the estate of", etc. which is not good to my dad without setting up an estate which is money he doesn't have & he paid for the facility with a personal check and credit card. They told me to return that check and they would send another check made out to my dad. Nothing yet after mths and dodging calls, etc. What they had went to my dad thru mom's will, not enough to probate. My dad needs his money???? My dad is 91, has dementia; I'm his poa.