When my mum had an infection she insisted the lady in the opposite bed had a snake going up her arm! She hates snakes. Must have been awful, when we went to visit she told me I wouldn't believe what happened on the ward at night. Very worrying but then we found out she hadn't been treated for four days for the UTI she came in with.
When she was transferred to another hospital she wanted to walk home sixty miles as she could hear someone abusing a child, my son. All in her head, but even now two years on she says she won't return to the hospitals, so I dread what will happen.
She does also tell me about the ten cats all different colours in her garden bouncing like lambs, the wallpaper keeps moving and is convinced the tall building behind the house opposite is amazing as its floating! I just usually say to her oh what a shame I missed it, or think it's okay now, or in respect of the building I bet they get a lovely view!
Don't worry it's all part of it I'm afraid, just don't contradict them, agree or change subject or offer a cuppa usually works.