I think all those things are fine! I dunno, I always feel like flowers and booze, even if allergies/not drunk, are such clear symbols of 'I thought about you and got you something nice'. (Speaking as a non-drinker who gets alcohol gifts sometimes.)

Buuuut yes, chocolate might be a safer bet, and you can always just go to a chocolate shop and choose something that looks nice - again, it's a clear symbol, even if you end up choosing something they don't like. And if you write a nice card you're golden whatever you give them, I think - they'll be touched no matter what it is.