Hello, the best place to find out this information is at the County courthouse at the Clerk's office where your mother's real estate holdings were located. You are wanting to ask to see the appropriate book of records which will have all of the deeds and other public records associated with the home recorded. Provided all of the owners since your mother had the deeds et al recorded.
You can also ask to find out who the current owner of record is paying the property taxes. We as Realtors can do this for you if we have the address of the property. However, many times the Owner of Record is a trust, Investment company, etc. Also, several counties now have their records online and you can search for the information yourself. Be careful though because there are some sites that look like the counties, but are actually paid search companies.
From your question I'm under the impression your mother may have had more real estate holdings than just her home. If this is the case, you may want to go to the expense to contact a local Abstract and Title company to do a search for your mothers' properties. Most of them have an attorney on their staff who will provide an opinion on the properties, including other rights that might be disclosed by the abstract. Just ask them for an estimate to give you an idea of the costs.
Hope this helps you and good luck. Should you have any questions or concerns, please give me a call 405 - 562 - 0886 or e-mail email@example.com