Only the rarest of horror movies can effectively pull that off without it seeming like a dodge, because the "it was all in her head!" ending is about as disappointing as a movie's ending can be, so realistically, we know we're either heading for (a) it's real, or (b) a shitty disappointment.

If anything, I thought they were still trying too hard to sell the "is she crazy?" angle even after we already knew she wasn't, that this plot was real. Shit or get off the pot. Or keep the entire movie from her perspective, which I think is the only way the "is she crazy?" angle could've effectively played for the entire film.

Thoroughly enjoyed the movie, just a very minor nitpick that I feel could've improved the execution.