1. You can use the peephole to see who's at the door (by approaching the door).
2. A visitor’s appearance is not related to hallucinations. Regardless of who’s at the door, detect anomalies.
3. If they disappear or return to normal, it’s safe to open the door. If they don’t, take your meds. Hallucinations may go away, or not. That means things might return to normal, or stay abnormal.