I’ll say it again and again, before you call the cops for anything, you need to remember what you’re actually doing. You are willingly inviting an armed person, who will not lose a fight or back down, who is shielded from legal consequences, into your situation.
Grandpa isn’t answering his phone or the door and you’re worried? Call a locksmith, not the cops. Cops will just kick the door or call the locksmith anyway, now you have extra problems