If she doesn't have a UTI (as GladImHere suggested) yes, it's normal for dementia patients. My 97-yo aunt does the same thing and I've called the manager of her in-home care company and explained that she will call people very bad names (like the n-word, which she never did prior) and so please don't send anyone who can't look past that language. They did find her a very excellent person. Also, an experienced home care aid should have tricks up their sleeves to get them to shower. Maybe you need someone with more experience. If it's a private company I would definitely call to discuss it. If it's Medicaid or social services I would still give them feedback but not sure if they are able to send a different person. Good luck!
After ruling out other causes, I'd explore if medication for anxiety or depression would be helpful. Sometimes, anxiety and depression can cause undue agitation that is unpleasant for them as well as those who care for them. After my LO's anxiety and depression were treated with medication, she became much more content and open to receiving assistance with her daily needs. Otherwise, her anxiety made her too nervous to accept help. Another thing that helped is when the staff were trained to work with dementia patients. Training and experience were helpful.
When last did she see a doc? She could have a UTI that is causing these recent behaviors. Has she been checked?