Both, you can Either save them or slay them :)
(SPOILER)
I'd like to think that it's a choose your own ending and choose your own adventure kind of thing :)
You get whichever ending you want, personally I'll keep the ending where the house is destroyed and the curse gets lifted but my family dies, since they weren't having such a nice life at least now they are free from the house even if it means they died 😂
doing those things are not required to beat the game... at least i don't think so, but it's kinda like undertale (except not an RPG), it's like undertale because you can do almost whatever you want, just to see what happens, also make sure to leave the fridge open after mom falls asleep on the kitchen chair.