How can I find out if my mother had a life insurance policy?
There is no easy or good or certain way to this: there is no central database, file, etc. for life insurance. All you can do is go through all her papers for any policies or correspondence relating to a life insurance policy; go through her bank statements and cancelled checks, for any payments to an insurance company that might be for life insurance (so you can follow up); and possibly call the major life insurance companies (e.g. Met Life) to see if they had a policy for your mother. Don't forget to look in a safe deposit box, if she had one. Sometimes you simply have to get lucky: my father was a WWII veteran and had a life insurance policy through the military that he never told me about and about which he'd forgotten. I only found it because in going through his papers, I found one old letter from the military insurer about the status of his policy, from around 20 years ago.