Dementia Anger Issues - bathing

My mom is in a memory care unit. They insist on giving her a bath/shower. It takes 3-4 people to get her to do so and she is very angry after it's all over. I understand that they have rules to follow....but when her anger leads to hitting other patients and they then pushing my mother and causing her to fall, I cannot see their reasoning for giving her the shower/bath in the first place. The family has asked for them to just do sponge baths but they don't seem to listen. What do we do?