My father was in the Navy. How do I find out if his wife, my step-mother is eligible for assistance?

Webb, there are a lot of questions about applying for VA benefits, and determining eligibility. You can start with posts by others, and see if your questions are answered.

Pay particular attention to applying to the VA directly, or one of the service organizations such as VFW or American Legion:

https://www.agingcare.com/search.aspx?searchterm=applying for VA benefits

Contact the VA

You may find this website helpful. https://americanveteransaid.com/eligibility.html?gclid=EAIaIQobChMIneGy-cTA3AIVWrbACh1SHwq1EAAYASABEgIFCvD_BwE

You must have the DD214 - it's a number the veteran was given upon his honorable discharge from the military.

I understand this is a complex and long process. My mother did not qualify because she had divorced my step-father before he passed.

Best of luck to you on this!