It's a difficult question to answer. She's not even sure she knows, beyond the fact that she could, and it had felt like the right thing to do.

"He has people who care about him. Any one of you could've asked me to if you'd known I could do it."

They hadn't, but given that she would've done it if asked, she didn't see a reason to withhold the offer just because they didn't. It's the closest answer she can find to the more complicated one, which was that he felt like someone she ought to care about, herself. She's not sure if that's her bond with Kylo, her tether with Luke, or just the envy of all of them for having a family at all.