Mom is seeing things (people) and feeling that they are in the house and taking her belongings. Could this be a medical issue?

Yes. It could be a reaction to medications she takes or she could have an infection. It could also be a symptom of Alzheimer's or other dementia. She definitely needs to see a doctor.

Take care,
Carol

It could also be a sign of vascular dementia....she is perhaps having series of TIAs....If she is not on any different meds....have blood work to R/O infection, then look into the possibility of Alzheimer's or vascular dementia..! Vascular dementia and AD are really close....My husband had the same thing happen, but worsened with paranoia added, he has been diagnosed with vas dementia and intermittent delirium! Get her to the docs!