Kathleen, like Roseanne said it is so different with each of us, but I would say(my Mom is 83) that I would not leave your Mom by herself for at least a week to see how well she does(would she come home with you?). Each Chemo is different on how it affects you...at least mine was.
Is your Mom active? That will help a lot if she is.
So sorry that your Mom,you, and your brother have to deal with this but glad you came to this site..Hugs,Ruby