24 YEARS old mortgage life policy found

Hi, I am trying to navigate a VERY messed up insurance situation. Mortgage life insurance policy from 2000, Husband and Mother in law listed on policy, Both passed away in 2001, Mother in law had dementia and destroyed All insurance policy paperwork so I only knew about the policy but had no way to know WHO it was with or policy and account number. Home for forced into a short sale, My children and I had to move out of the house,I found a thread of information in 2023 and started my trip down the rabbit hole, I located the name and contact information for the insurance company, I contacted them, of course AFTER they confirmed the existence of the policy, since I wasn’t listed on the policy they refused to speak with me about it. But since they learned from the call that the policy holders had passed away years ago, they REFUNDED the PREMIUMS to the state Treasury department. I HAVE received a check for $150.00 the policy was for $160,000 & the home sold for the Short sale amount of $55,000. So I believe that the insurance company owes $160,000 which would be sent to the mortgage company and the mortgage company would then owe me a refund of $55,000. If I am correct. I WILL be contacting an attorney on the matter, but I don’t know what to do about the $150 premium refund check from the state Treasury department. Should I hold on to it, If I cash it would that be accepting settlement for payment ? Please advise me.