The last words from the moon . . . perhaps

Officially . . . .

"America's challenge of today has forged man's destiny of tomorrow, and as we leave the moon . . . peace and hope for all mankind.  God speed the crew of Apollo 17"

but

according to 'most',

just before lunar liftoff Gene Cernan (the last man on the moon) showed his mastery of words and said

"Lets get this mother out of here"