An even more likely explanation for MOB would be in reference to the Blood gang. During the time 2Pac had just recently become affiliated with Suge Knight and Death Row, and in turn, became involved by association with the MOB blood gang in LA, which Suge was a member of. In this song, 2Pac was calling out major street figures (Jimmy Henchmen, King Tut) who are very dangerous individuals. 2Pac in this lyric “Nigga this is MOB” was letting it be known, he has back up now for protection to combat them (Henchmen and Tut) on the streets.
This video is processing – it'll appear automatically when it's done.