It was all a dream. The end.
I hate to be the asshole, but the word you're looking for is "canon."
They're all canon, at least until Bloodborne 2 comes out. From a design perspective it'd make the most sense if the hardest ending to get ends up being the 'true' one.
Also, Kro is wrong.
@Domhnall Naw dawg, you know, that cannon, from the Powder Keg Hunters. :D