What happened to the nationalists after the civil war?

they were driven out of mainland china.
they centralized their power in major cities.
they gradually lost all power in china.
they revolted against their party leader.

The correct answer is the first option. 

Members of the Chinese Communist Party won the Civil War, thus resulting in the members of the Nationalist Party being driven out of China.

The second option is incorrect, because they lost the war, and thus were unable to centralize their power in major cities.
The third option is incorrect, because their loss of power did not occur after the Civil War.
The fourth option is incorrect, because this did not occur after the Civil War.