She doesn't have
schizophrenia. If there has been gradual decline in memory for recent events and other intellectual capacity, she may have dementia.
It is common for dementia patients to have
hallucinations (seeing and hearing things that aren't there) as you describe. If her memory problems have started recently, she may have
Lewy Body Dementia (LBD). LBD may also have tremors and rigidity.
If she has had memory problems for a few years and only now has hallucinations, she may have Alzheimer's. You should take her to a
psychiatrist to get proper treatment. The psychiatrist may order a few blood tests as well as a CT scan to find out any medical conditions that may cause these symptoms. This way any reversible cause can be treated and even if there is irreversible disease, its progression can be slowed down by treatment.
If there has been sudden change in mental state over a day or two, such as
disorientation to time and place & distractibility, she may have Delirium and needs urgent medical attention.
I hope this has answered your question.