Oh well she'll definitely be friendly! In-canon she knows a man who has two daughters and I've always had the headcanon that she helped make sure they were doing alright when was having troubles. So she's no stranger to being nice to kids, she's just not necessarily the greatest at all the other stuff that comes with raising them.

He's more than welcome to come if he can keep up (she's almost seventy, though, so he probably won't have too much trouble with that). Her routine almost certainly involved interacting with a few non-humans/rougher types like Toriel, Booker, Stein, etc, so he'll be exposed to them through her, at least.