The Babadook written and directed by Jennifer Kent

This film seemed to have a lofty goal of ending with a single resolution, while having multiple interpretations of that ending:

1. Mom tamed the beast, and it now lives in the basement.
2. Mom went nuts, and this is her "reality".

However, most of the film time is spent on a better ambiguity, i.e. whether the babadook is:

1. the kid making mom go nuts
2. the mom going nuts
3. some other beasty

In the end, this film came across as depressing because Chaos arrived, overwhelmed, and destroyed a normal person who just wasn't flexible enough.