Only bathe an indoor cat if they got something that needs washing off of them. Anything else will be cleaned by their own grooming. They have natural oils that get washed away when you bathe them and will dry their skin.
Once every 2-3 months, and NEVER use human soap on them, get a special one that doesnt itch their eyes. Also, never thrpw water to the head, especially to the ears. If she keeps bathing the cat once a week it will get sick, or get a nose/ear infection. Tell her to STOP! I have 2 cats.