Candidate moves : a3 , to prevent Bb4 threatening to swap off potentially weak bishop
Nh3 , developing , retaining castling options

or 0-0-0 , which i think is too committal , and dangerous as black's qside attack looks quicker than white's kside operations.

I personally favour Nh3 and if Bxh3 Bxh3 and 0-0