Creepy Independent Film of past five years – help! What’s the title?

The movie was a psychological thriller about a young woman who had a female caretaker acting in the place of the mother, and who kept the woman dependent on her via gaslighting: telling her she couldn’t think for herself, handle daily tasks, or even bathe or clip her own toenails. It’s a dark film and I recall two of three main characters being killed during a twist of an ending.