Hm. I'm wondering if you have a bad spirit in the house like Karen suggested. I second the idea to smudge the house. Set the intention that either all spirits leave or only the highest and best can stay. Command any dark spirits to leave in the name of god or Jesus or whatever good energy you trust. Really, I'm just wanting to repeat everything Karen said.
What an unnerving dream. I'm glad you have your step mom's good spirit looking out for you.
I agree with what has already been said above, but how old is the house? Is it located in a historical area? Is your real mom now passed over? If she has I would say that she is telling you that something is not right about the house you are now living in. Keep us up to date about any strange activity that takes place either in your dreams or in reality!
And also welcome to EC may your journey here stay with you for the rest of your life!