Nominative: مُسْلِمُونَ — wāw, with ḍamma on the preceding mīm.
Accusative: مُسْلِمِينَ — yāʾ, with kasra on the preceding mīm.
Genitive: مُسْلِمِينَ — yāʾ, with kasra on the preceding mīm.
Remember: Wāw and yāʾ are the actual case markers; the nūn following them is not the case marker.