I thought the ending was pretty obvious... (Spoiler)
So I just got back from viewing Krampus a second time (I really liked it). This time, watching the movie and knowing what will happen, the ending seemed pretty straight forward.
So Max wakes up, thinking the whole thing was a dream. He looks out the window and sees his neighborhood, normal and at a reasonable snow level. He runs downstairs, the house is restored, and everybody's getting along but don't seem to remember last night.
Then he takes out the bell and everybody exchanges glances because they all had thought it was a dream and realize what had happened. We then exit the house and see that it's in a snowglobe amongst many in Krampus' workshop.
Based on everything in the movie, I'd say they were definitely given a second chance and not really in a snow globe. First off, there was a huge theme of self-sacrifice for the greater good that all of the family eventually learn, that wouldn't make any sense given a dark end.
More importantly the way the scene is done just makes it seem obvious they're not in a snow globe. Max sees the neighbors' houses. When we back away from the house, the neighborhood is in the reflection of the window. The reflection goes away once outside of the snowglobe and the house becomes a very obvious toy. It's also important to note that none of the lights are on in the interior of the snow globe house emphasizing how NOBODY IS HOME. I'd say the snow globe is a little trophy for Krampus. Plain and simple.