“Matriarch” (*1/2 out of four) was a dreary horror thriller about a woman (Jemima Cooper) who survives a drug overdose and is then afflicted with a mysterious illness and subsequently returns to her childhood home to reflect on her life and confront her personal demons but instead comes face-to-face with a real demonic horror instead. Film attempts to deal with serious elements of drug addiction, repressed childhood memories, and PTSD but results are gloomy and boring. Cooper does what she can with a one-note role. Originally titled “Wormeater.”