your mother in law can take tab reglan 10 mg thrice daily before food.
For diarrhea T.Imodium
4 mg stat then 2 mg 2 hrly till motion stops
Do a straight x ray of abdomen to rule out sub acute intestinal obstruction
If diarrhea still persist then inj Octreotide
150 mcg subcutaneous thrice daily for 5 days along with T.Ciplox TZ twice daily after food for 5 days.
Regards and take care.