The List
There are 138 4 letter words with M as the last letter. The highest scoring is AZYM at 18 points in Scrabble.
AHEMALUMARUMATOMAZYMBALMBARMBEAMBERMBLAMBOOMBORMBRIMCALMCAUMCHAMCHUMCLAMCLEMCOMMCOOMCORMCRAMCREMCRIMCULMDEEMDERMDOOMDORMDOUMDRAMDRUMDWAMEXAMFARMFEHMFERMFILMFIRMFLAMFLIMFOAMFORMFROMGAUMGERMGEUMGISMGLAMGLIMGLOMGLUMGORMGRAMGRIMGRUMHAEMHALMHARMHAWMHELMHERMHOLMIDEMIMAMITEMKAIMLEAMLOAMLOOMLYAMMAIMMALMMARMMUMMNAAMNEEMNEUMNORMOGAMOVUMOXIMPALMPERMPIUMPLIMPLUMPOEMPRAMPREMPRIMPROMREAMRIEMROAMROOMROUMSAIMSCAMSCUMSEAMSEEMSHAMSHIMSKIMSLAMSLIMSLUMSOOMSOUMSOWMSPAMSPIMSTEMSTIMSTUMSWAMSWIMSWUMTEAMTEEMTERMTHEMTOOMTRAMTRIMTURMVEHMWARMWEEMWHAMWHIMWHOMWORMYELMYLEMZOOM