Berkshire County (2014) online

Kylie Winters, a bullied and self-loathing teen, reluctantly agrees to babysit at an isolated country mansion on Halloween night. When a small boy in a pig mask appears at the door trick-or-treating, Kylie's night transforms into a horrifying and violent cat-and-mouse game. She must go beyond what she ever thought possible if she and the children are to survive the night.