Couple hours with diarrhea, bowel movement turned bloody with stringy stuff attached. what could that be a symptom of? (mom is 89; mex food that night

Go to the ER: If you have diarrhea (or someone else has it) that becomes bloody - this needs urgent medical evaluation. It could represent an invasive food borne pathogen, or possibly some ischemic issue with the gut (as in an older person). Blood losses from the GI tract can be significant and need proper evaluation. I would try to get seen by a doctor ASAP.