Mom sits in dirty depends. What can I do?

Lately I've noticed, that Mom does not always clean herself. She will get out of bed and get dressed right away. Then she will say, "I'm all cleaned up and dressed" If I challenge her and tell her, that she never went in the bathroom, she gets angry and says "I WASHED MYSELF". Even though the Depends and the pee pad I left for her, haven't been touched. Likewise her washcloths are still dry as well. She has both cloth washcloths and the large size wipes. But it appears she's using neither! Today she smells like she is sitting in soiled Depends. I asked her to check herself, and she just blew up at me. " I'm clean, I washed myself". What can I do?