Penni, stay with me a moment. I'm not nominating Gracie for mother of the year. Legally - there's the operative word - she didn't do anything wrong. She left her son in her disgustingly filthy apartment while her husband was still passed out, probably thinking it was okay based on past experience. If the bananas are rotting or the whatever that was in the fridge, those are not offenses that would cause her to lose custody. I think you have the pot issue answered... 
Now she's in the child welfare system and will get tons of resources to help her be a better parent. I hope for the kid's sake that it sticks.