Translation:Mijn buurvrouw is op vakantie, dus ik zorg voor haar kat.
Why is "buurman" not accepted here?
...so I take care of her cat.
So when is "met vakantie" used? I have seen only one exercise with it.
Both "op vakantie" and "met vakantie" are used equally in these types of sentences. (So they are both accepted) ;)