According to you, her own biological father will not talk to her and she was the cause of her biological father and mother getting divorced. On top of that, the granddaughter menaces you with weapons and they rifle through personal areas of your home when they visit. Additionally, it sounds like your husband started "fathering" this daughter at 18, but her mother has been dead for at least 9 years.
Something is seriously wrong here, but for the sake of argument, let's say you are being truthful, and this demonically possessed, non-biologically related to anyone and her devil offspring and spouse show up unannounced to wage war on you and your home at various times. Why is your husband allowing this? Why in the world would you marry a man who would allow this? Why are you continuing to blame the daughter and NOT your husband, who continues to allow this?
If it is truly THIS bad, I'd work with my husband to find every last thing in the house that belonged to the mom, put it in a box and mail it to them and ask them not to visit any more - if they want to see "grandpa" they can meet him at a restaurant, but YOUR home is off limits. If your husband cannot agree to this, then you married the wrong man.