Is her new medicine really a good idea?

My mother has dementia and seizures. She is taking Dilantin and Kepra for the seizures, 300 mg. a day of Dilantin and 500mg Kepra. Today the doctor at the nursing home prescribed Seroquel. She is already unsteady on her feet and falls frequently. I'm worried that this new drug will make it worse. I don't know why he prescribed the drug. She has been at the nursing home for about 3 1/2 months since breaking her hip. Before the broken hip, she was in really good shape and could still live by herself. Since breaking the hip, the dementia has worsened. The staff at the nursing home thinks I'm being overly worried. I don't think so. What do you think?