Could my elderly mother be having symptoms of dementia by repeating things constantly and talks in a frenetic, disjointed fashion?

I agree that your mom should be seen by her Dr.

Obviously we can't say that your mother has dementia, but those behaviors are all consistent with a dementia diagnosis.

How long has this been going on? How old is Mom? What is her health like in general?

Whatever the causes behind this behavior, the appropriate thing to do is have her evaluated medically. It is possible there are short-term causes that could be cleared up (such as a uti) and if this is, indeed, dementia, then it will help you to know what is going on and what to expect and perhaps even how to deal with these symptoms.

Ya think?