After you made 4 more bar upgrades (besides the first $20,000 you gave Aunt Lily), some Dixie Mafia will automatically show up...its real easy, only 5 or 6 goons, finish them off, interact with the Dixie leader (who should still be alive, but he'll be on his knees) IIRC, he'll still show up as a red marker on your mini-map, and the achievement pops after you're done talking to Aunt Lily