It sounds as though your Mom is having psychotic episodes. That doesn't mean she is "crazy", or will be diagnosed with schizophrenia, or other psychotic illness. Sometimes, certain medications can cause psychotic symptoms, or even effects of certain diseases (when a diabetic's sugar gets VERY high or very low, this can happen).
What I am saying is this is definitely something she needs evaluated for. Understandably, she is going to be resistant and scared when you talk to her about this. Be VERY compassionate, and approach her that you just want her to have a thorough physical, to rule out anything physical, and if needed, a consult with a psychiatrist. If she seees a p-doc, reassure her that she won't be "locked away"...there are a lot of options out there....and they will have to look at many options for diagnosis, and treatment. If she is completely functional in daily life, and this is a new thing for her...this can very well be managed as an outpatient with meds.
Does your Mom have ANY history of mental illness, any mental illness in her family? How about substance/alcohol abuse? People withdrawaling from these kinds of things often having psychotic episodes. It could be something as simple as her doc cut a med that should be tapered that is causing these symptoms. My main point is.....for YOU, and for your family (share this with them)...this isn't necessarily an indication of a big and bad mental illness. Not to mention, illnesses like schizophrenia VERY commonly first surface in the late teens, early twenties. It is very rare for a mental illness like schizophrenia to appear in the later years.
When dealing with your Mom, be VERY honest, yet caring. Tell her, "I'm sure you see what you claim to see, you just have to understand that WE don't see it, which is why we're worried about you." Don't discount what she is claiming to see.
Best of luck...hope it works out!
Not wanting to sound crazy myself, but did you ever do a history check of the area to see if there is anything similar accociated with the area maybe dating back in time? I know a few spiritualists who see a lot of things I don't see. If we were to committ them all on the grounds of what they claimed they could see there would be no room left in mental hospitals. Don't get me wrong here. Not saying your mother is not delusional. She may well be. But what if you said ' yes, I can see them '.? Other option would be the logical option. The doctors. For evaluation of the mind. Probably end up on some form of strong tablets. Not for anxiety. Lord help me spelling this word, schitzophrenia. I know I spelt that wrong. MedHelp might have a forum that deals with that condition. You might get better answers over there. Because that is what it sounds like if we are ruling out all normal posibilities.