1. Medical, etc. MUST be done in country of the interview- Nigeria.
2. Current wait time for a tourist visa interview in Lagos is 760 calendar days.
The chances of a B2 visa, even if she had an interview, are extremely slim. Getting a B2 visa after having displayed immigrant intent is very, very unlikely.
Veteran status is not considered. Unfortunately, nothing in the legal US immigration system is fast, fun, easy, or efficient.