What happens to target creature when Essence Scatter is played?
Essence Scatter counters a creature spell, and countering a spell is defined in the Comprehensive Rules 701.5a:

To counter a spell or ability means to cancel it, removing it from the stack. It doesn’t resolve and none of its effects occur. A countered spell is put into its owner’s graveyard.

Note that technically there is never a creature in this case: a spell becomes a creature only when it enters the battlefield.