Grandmother on laxative because of antibiotic. Have no idea how she defecates. What is the sanitary and proper way to dispose of feces??

Most of you know that my grandmother (who has severe Myositis and is confined to a wheelchair) pees into paper cups in the kitchen because she can’t go to the bathroom. She’s now on a laxative because she has pneumonia and the antibiotics messed with her system. Well, just a few minutes ago I noticed her obviously butt naked at the kitchen sink and I didn’t know if the laxative took effect and she was defecating in an extremely unsanitary way.