Keeping Mom warm enough during a bath. Any advice?

In addition to the whole house heat, I use a portable electric heater. It looks like a small box and does a great job. I like the idea of heating the towels too.

If mom is cold all the time, perhaps you can use the small heater close to her to heat the area she is in without having to heat the entire house. They generally have thermostats built in so that you can adjust as needed.

Also, if there are windows in the bathroom, there will be a heat transference, whether you feel it or not. Be sure there are drape or curtain window coverings, not just venetian blinds or shutters. You can even temporarily thumbtack a sheet or something over the window. It will help more than you think.

Older people have such thin skin and thin blood that they just feel the cold more than younger people do.

My parents also get cold bathing. We turned the heat up in the whole house to get it toasty as possible when it's time for a bath, then do the same thing you do. We have forced air heating, so we can put the towel over the vent so it can be toasty warm when it comes time for drying. If your mother has a clothes dryer, perhaps the aide can put it in during the bath so it will be warm. Besides doing these things, I don't know what else can be done. Fortunately, it is just a temporary discomfort.