Stupid question
 

I have a 84 190D that me son is driving, he hit a curb a few weeks ago. I don't know what it is called that he bent back. The passenger side wheel is almost hitting the back of the quarter panel. Everything is bolted up to this part, the spring, the shock, the ball joint is in this part too. I cant think of what it is called, any one know? Thank you.

Sounds like he bent a control arm.

Is that what it is called? Thank you.

I think you mean the idler arm.

Rob

I think Skippy had it. Sounds like lower control arm

Yes you are right it is the control arm.
If it is bent I would also replace the idler arm.

Rob

This sort of damage also twists the frame, you may or may not need to get it straightened out after replacement of the arm.