Our 95-year-old mother is experiencing visual problems leading to hallucinations/seeing things that aren’t there. She is afraid to stay alone.

It's important to see the doctor regarding this. Many forms of dementia and other disease processes have hallucinations as part of the manifestation. Lewy's dementia is famous for very real visual hallucinations and many people with Parkinson's suffer from hallucinations. In my brother's early diagnosis of probable Lewy's Dementia his excellent descriptions of his hallucinations were part of the diagnosis (along with loss of taste and smell, altered gait, foot tapping, occ. swallow problems.
Hallucinations caused by visual problems is rare. This is usually a problem in the brain's circuitry.
I would suggest, if you are POA, that you attend with your Mom an exam with her doctor. He may refer her on to either opthalmologist or neuro-psyc MD.
The more precise Mom can be with what she is experiencing, when and how often, the more likely they are to come up with educated guesses or diagnosis.
Wishing you good luck and hope you'll update us after Mom sees her doc.

You can hire a caregiver to do over night shifts.
I have to wonder though are the hallucinations a symptom of another condition that should be treated.
There are medications that can help with hallucinations and anxiety.
The big problem with medications like this is that they can increase the risk of a fall.
It might be time that either mom does have a caregiver and maybe not just at night or it might be time to look into Assisted Living.

Side note if you posted on this site hoping to hire someone this is a forum of caregivers that ask and answer questions. This is not a site that provide caregivers.

First of all, you need to have an idea of what might be causing the visual hallucinations. Are they caused by poor sight or from dementia? This is how you will get a preliminary idea: If the person has soundless visual hallucinations, and they are aware that they aren't real, it could be a case of Charles Bonet syndrome. A condition that affect people who are losing their sight. On the other hand, If the person has visual hallucinations with sound (visual/auditory), and think they are part of reality, this could be a sign of psychosis (from dementia or from other type of mental illness). If they are caused by poor sight, you can consult an eye doctor. If they are from dementia, you will consult a neurologist or a psychiatrist.