Text of Hovel: When you buy a Victory card, you may trash this from your hand.
Text of Haunted Woods: Until your next turn, when any other player buys a card, they put their hand onto their deck in any order. At the start of your next turn: +3 Cards.
Note that both cards trigger in this scenario on the exact same thing: You bought a Province.
There is no formal distinction between both card's effect, both a are triggered effects. Since they both instruct you to do something, you can order them as you want, probably trashing Hovel first.
Again, there is nothing that indicates that Haunted Woods' effect should be treated with any preference over Hovel's. Both are 'on-buy' triggered effects.