The replies are all good advice,urine Infections, dehydration can cause these symptoms,and can make you very ill,I am 52 and was admitted to hospital with a fever and seeing a Indian lady in my bedroom and rambling about it!
But she was real to me! It was the fever doing it!
But it honestly sounds like dementia,my dad was like this ,everyone was stealing of of him or against him.
My friend's dad was convinced a orchestra has set up in the trees,but thinking they are being spied on and stolen from is very typical for dementia,
I found the best thing is not to deny what they believe,it will just make them agitated as it's their reality, reassurance ,my dad was sectioned and we told him he was in hospital for a chest infection as it calmed him down ,
Speak to a manager or senior nurse,they may not be aware of the situation,and it's essential they know of any possible progression in any illness ,or check for infections etc.