Who will host the dinner/lunch

Hi teachers,

Are the following sentences correct?
Who will host the dinner/lunch?
I’m very thankful to you for hosting us in such a beautiful manner.

Many thanks.

They are both correct.
The second sentence could be improved by saying "Thank you for hosting us in such a beautiful manner (or so beautifully.) Readers believe what you say directly; passive sentences sound like you are equivocating, like you want to be able to weasel out of what you’re saying.

Even given the suggested changes, I think the sentence ‘for hosting us in…’ sounds distinctly odd.

I’d suggest:
Thank you for being such gracious hosts.

In addition to what Bev has said, I think the word you need is “grateful”, not “thankful”.
Look at Alan’s explanation of the difference between “grateful” and “thankful”: