The only instance of USC roommates winning MVP awards in major professional sports is
Mark McGwire and Reggie Jackson However, this is debated as they didn't actually live together *during* their playing careers. They were teammates at USC, and were known to have a close friendship. McGwire won the 1986 AL Rookie of the Year and Jackson won the AL MVP in 1973 and the World Series MVP in 1973 and 1977.
There's no other readily available documented case of USC roommates winning major professional league MVP awards.