She isn't being unreasonable she has a disease which prevents her from following the normal social convention. In our world she appears to be unreasonable but in her world she is talking to her little girl and who knows perhaps she took great pride in having her little girl's hair cut in a certain way and it was very important to her and now she is reliving it. Whatever the thinking behind her reaction one thing is for certain - she ain't going to change - not because she is being unreasonable but because she has a disease which prevents her from reasoning and compromising and that's all there is to it. It isn't mean, it isn't malicious, it is a disease.I wouldn't in these circumstances. Poster's views and self-esteem are every bit as important as her mum's. Especially a mum with dementia who is being totally unreasonable. A break will be good for them both.
All I'm thinking is how Poster will feel afterwards. Will your regret not making your peace with your Mum. Perhaps people are right, perhaps a break will mean your Mum forgets about your hair, perhaps she won't - who knows, one thing is certain - dementia is unpredictable and that must be more uncomfortable for the person with dementia than it is for us because we can walk away, they can't.