Good luck. You might find evidence of this in corporate records, if they still exist. But no insurance company would pay out on the basis of that sort of evidence.

If it’s flood insurace – that’s a US government insurance program – you might find evidence in old US government archival records of coverage back then. But other insurance (fire, theft, etc.) is likely long lost, since the policies would have expired 50 years ago.

Check with the Department of Corporations for your state. When a corporation gets taken over or goes out of businees, they have to file with the state.

My grandfather bought a life insurance policy during the Depression, my mother remembered someone coming by the house once a month to collect the payment. It was only a few hundred dollars. When he died in 1985, my mother went to the State of California to find out who owed on the policy. My mom got a check out of it.

What do you know about the business, insurance company or anything related ?

You could try contacting the insurance commissioner for the state in which the business was located or you could try contacting the insurance commissioner of the state in which it was filed.

they could tell you your best options.