I used to live in Carmel Valley in a TownHome, and it always had issues with mold that needed to be remediated periodically.
The main issue was the shower in the master bedroom. It was a lame design because all the steam would just go into the bedroom and there was no fan. We never used it unless we had guests, and instead used the shower in the center of the unit that had a fan.
Second problem was the windows. They were single pane windows with a metal frame. Anytime it was cold outside, moisture would condense on them causing mold. I’d clean these with a 10% bleach solution twice a year to mitigate it.
The blinds would also get a bunch of mold on them and required cleaning as well.
If she is seeing mold on the windows, then she definitely needs to clean it with bleach. The issue there is that due to temperature differences between the window and the air inside, air tends to circulate past the mold on the windows carrying spores throughout the house.
When cleaning these windows, you don’t need to use a lot of bleach, you can just dip a q-tip in a bleach solution and hit the worst areas first. Just make sure you do it during a day when you can leave the windows open to air out, and wash the bleach off with fresh water on a sponge 10 minutes later.