The emperors of Mali were known as Musas. Mansas. Malias. Menahs.
The correct answer is "Mansa".
"Mansa" means "emperor" or "master" in the Mandinka language, one of the main languages of the Mali Empire.
The confusion here might come from the most famous of Mali's emperors: Mansa Musa, but Musa was his private name, not shared by others.