Do i need to replace the whole arm or the bushing. I hit a curb hard.

 

You can get the bushing separately, my Carquest listings show the Moog # being K200366
and Raybestos being 565-1415. You will need a press to remove/install them however.

Also it doesn't look too bad from your pics but its hard to tell, is there play or rips in the bushing now? anything bent to impede the arm from swinging down?
Grab some under shots if you can too

 

There appears to be no other damage, just slide the control arm back and the tire rubs the back of the wheel well.