im on my friends account to ask which should i do for mma?

find a gym that will train you rocky style.

i think dojo B is the best because you already have the karate background, and in MMA you will need to utilize bjj for submissions, muay thai and boxing for standup and wrestling for takedowns and takedown defense at some point in sparring or in a fight, its better to have all around skills so that you dont have holes in your game.