Doesn't recognize own home
When it happens
Why it happens
Brain changes causing a disconnection from reality can make even familiar places seem foreign.
What you can do
Don't try to insist, "But you are home!" There's no harm in gently pointing this out the first time, but if you meet resistance, drop it. The person isn't capable of joining your reality.
Go along with the person's interpretation. Maybe your home is "her" home, or her home is a hotel, or a cruise ship. You shouldn't go out of your way to pretend this is the case by adding bellhops, of course. But ride out the conversation: "Yes, I have a lovely room here, too."
Pay attention to the emotion, not the specific facts. Making sure the person feels comfortable and safe is what counts.