House dilemma

We have to move out from our current house because our landlord is selling his house and is moving in to this house. We have two options and we're not sure which is the best one, so I'd love to get some perspective from other people. We have two small children and a dog.

House A: Costs about 20% more than house B. Is right across the street from my SOs work, which also means we could do with only one car. Gas and car insurance is very expensive where I live (European country). Has a huge garden. Has a basement with great storage possibilities (which we need). Floor plan is good, has a kitchen, living room, office, bathroom and a room that could be a playroom downstairs and two big bedrooms upstairs. Is very run down, though. But I see this as a possible good thing when you have two wild kids. Is located in a small town with access to decent public transportation and a grocery store. SO knows landlord, is a good guy.

House B: Is out in the middle of nowhere with no grocery store in walking distance. I don't have a driving license yet because it's very expensive and I'm breastfeeding so I'm unable to take any lessons right now, will do in the fall though. Is owned by my SO's aunt which we have a great relationship with. She has said she will drive me anywhere I need to go, but I hate being dependent on anyone else like that. Is a newly renovated house with a garden. Is smaller than house A. Has public transportation, but not as good as house A. Since it's his aunt owning it though, we wont ever have to think about having to move out, which is always a risk with someone else.

We are saving up for our own house, but it's quite far away as you need to have 20% of the value of the house in cash before you can get a loan. As you can tell, I'm definitely liking house A more, but house B has it's pros, being cheaper being one of them. I also don't want to be rude to his aunt, feels a bit rude to decline her generous offer. But, I am a bit afraid of renting from a relative, if there was to be issues. I can't imagine there being any issues, but you never know, you know?