Surely Bd2 is a better move?

why is this the best move? Surely Bd2 or Bb2 is better???

White has no bishops. Preparing to castle with Ne2 results in Qd1#, if that is what you meant.

I should say light square bishop. This is a precarious position and white would probably be happy to trade queens and get castled

This move results in black trading a rook for a bishop at least after qxc3+. Bd2 or Bb4 prevents this trade???

Qe2 is best. If white moved Bd2 then black simply castles long 0-0-0 and therefore has the rook and Queen lined up to take that bishop. The white queen will then need to move to Qe2 to defend anyway on its next move. So your suggestion Bd2 would protect the pawn but really more is at stake for white here. White can't castle either side, so is really stuck without offering the exchange.