Preposition

(for) is correct; however "to you" is not correct - write this will become Chinglish sentence structure or not a native English speaker sentence.

It is because "for all that you have done" has identified the thanks is "to you"; so the correct English sentence/speaking is:

I am so grateful for all that you have done.

I am so grateful to you for all that you have done.
I am so grateful to you for all that your mother has done. You asked your mother to do it.
I am so grateful to your mother for all that you have done. Your mother asked you to do it.

Yeah,it's correct