Mother had a spat with the caregiver and I don't know how to handle it. Any suggestions?

I have two caregivers, one from Monday through Friday and the other on Saturday and Sunday. My mother liked the one during the week more than the one on the weekend. I like both CNAs and think they are wonderful with my parents (my father has dementia and is bedridden and my mother has mobility issues). My mother tells the caregivers to wake my father up to eat or to change him. When they wake him, he becomes angry and lashes out. So it is best to let him wake up naturally. But he may sleep past breakfast or past lunch. The nurse has even told my mother to let him sleep. My mother prods the weekday caregiver to wake him up and my mother is sometimes, no most of the time, not very nice to the caregiver over this. Well, this evening when I went to give my mother her evening medicine she mentioned how she does not like the caregiver because she doesn't do what she asked for my father. I asked my mother does she want to get someone else and she said no. I can't rely on what she says because she switches things around, one week she likes this one and the next week she doesn't. My mother got very angry at me because I told her I don't like to hear negative talk about the caregivers and I will investigate myself. She said I was a bad daughter and exclaimed, I am your mother! Like how dare I disagree with her. She talks to me as if I were a child and does not want to hear anything that is a contrary opinion. I do a tremendous amount for my parents but I find her to be rude. Every single day, either morning or evening, we have some sort of tiff over what has transpired during the day. I believe that the caregivers have a very difficult job and I don't want my mother to be rude to them. How can I handle this? Any suggestions would be very much appreciated.