Solution #1 (Alternative solution in bracket)
People on Left Bank Crossing the River People on Right Bank
    MMMCCC @ Start
  CC ( MC ) MMMC ( MMCC )
C C ( M ) MMMC ( MMCC )
C CC MMM
CC C MMM
CC MM MC
MC MC MC
MC MM CC
MMM C CC
MMM CC C
MMMC C C
MMMC CC  
MMMCCC @ Finish    
Solution by  "Interactive Fun Puzzles"