I have a really strange feeling that your mom's accomplice is a cop... maybe even at the same police station, you're planning to go to. Maybe calling the FBI would be a better idea. Get as far away from your mom as possible in the meantime. I'd say at least 3 towns or cities away. If the accomplice is a cop, and they find your grandma, all they'd have to do is bang on the door & yell "Police! Open up!" I have a feeling your grandma would open the door, regardless of your instructions to her.