Mom refuses to see doctor for dementia diagnosis

My 89 mom started hearing someone making noises at night in her backyard about 1 year ago. (She's never seen him.) I wrote note to her doctor about this before a visit when this first occured. His office called me to say it is auditory hallucinations and she needs to see a psychiatrist because he is not comfortable prescribing meds for this. Being that she told the doctor's nurse that I thought she was crazy, I've tried convincing her that there could be causes for the noises (like urinary track infection, meds, etc.), but she is certain she is hearing "the man". Even though it is very much a concern, I stopped trying to get her to see another doctor and it seems that she stopped hearing him and she was so resistant and gets angry. More recently she is hearing him more often. I would like help with any ideas of how I could get her to get this checked. Are there meds that can help? I would appreciate any information. My mom's nature is that she is very independent and resists helps with house and yard work. She does well otherwise, she knows she needs to exercise -- gets up and walk in the yard. She knows she needs to keep hydrated as it is very warm where she lives. Another issue is that I am 70 miles away from her, so I can't stop by for a quick visit. I have started staying with her overnight one day a week.