Elderly Mother in law has Hallucinations

My mother in law is 84 and she is seeing things from when she was in hospital last week.

From horses in the field to seeing a man woman and two dogs in the field next to the hospital and seeing a teddybear breathing in front of the couch and ants in the hospital and worms on the sitting room floor.

She has had tests in the hospital from head scans to bloods and urine.

Can you please help?