Are these sentences OK?
I finally met someone that cares about me.
What do you angry at most?

Question

Answer

The first one is fine but would also be fine with 'who'.
http://www.quickanddirtytips.com/education/grammar/who-versus-that

The second one is incorrect.Two possibilities:  What are you most angry about? What/who makes you the most angry?

Answer

someone WHO cares about me. We can't use THAT with people
and the second: the expression is get/be  angry WITH.

Answer

I see yours true, but let me add my suggestion:
I finally found someone who feels solicitous about me.
what makes u angry at most?