While I haven't been taught what to do or think....lol I'm going to give my opinion anyway.
I would ask if both parties are consenting, if so, leave them be.
I sure wouldn't want to step inside and shut the door. It would be my luck, I'd get a harassment charge or some other weird charge.
As for calling the wrong name, heck, that could happen even if you don't have dementia!
Actually, the question says initially. Therefore, I would think you would step inside and close the door, then ask if both parties consented. If so, leave and shut the door behind you. So, I would pick C.
OH.....be careful posting questions.