How do you tell your Mom to change her clothes, without offending her?

Pam: Worked for me!

Maybe modesty has a role in this. There are cover-ups, available in adaptive clothes catalogs, that you wash around and lift up, allowing the disabled or elderly, their dignity.

Having been a caregiver and cared for I can see both sides of this issue leaving out the dementia aspect.
Elderly women don't like being exposed.
They don't like being cold and they don't like being bossed around in a condescending manner or treated as though they are half baked even if they are at the time.
Make sure the bathroom is warm and free of drafts.
Have plenty of warm towels available,
Only uncover the part you are actually washing.
Give the patient a wash cloth to wash the "front" of the genital area, then have them turn around and do a really good job right through from the back if needed.
As each body part gets washed dry and wrap in a warm towel and only do small parts at a time, drying immediately, for example only do one arm at a time not the whole front of the body.
I am in my third month of hospitalization at present and have been bathed in all kinds of manners, some kind and cozy and some i'd rather not describe. I no longer care about modesty but what really got to me in the first hospital I was in was the use of male aides providing the most intimate of care. Personally I can't pee if some strange male is watching me - you might as well put a toilet in the middle of a parking lot with no walls!!!!!!!! Needless to say I am never going back to that hospital again ever. To me that has nothing to do with modesty it is plain degrading.
Anyway back on subject as others have said when you are caring for a loved one with any degree of dementia you just have to be in charge and get the job done even if it means enlisting the help of other family members to actually get them in the shower. Clothes simply get removed from the room and washed and only a small selection left in reach. As long as undies and socks are changed at least daily I see no problem to wearing something more than once as long as it is not stained.

I think u could have asked for a female to help u. Mom was in rehab and called for a CNA to take her to the bathroom. A male came and I asked if he was going to help her, he said no. He just answered the call and would get a female.