The dceadron,Ativan and Zofran combo works well for controlling nausea and vomiting, so you need not to worry too much. Percocet is for pain but should be give like every 4-6 hours as needed. If you give Percocet on a as needed basis without the time of how many hours apart fron each dose of Percocet,your mom may get too sleeply. Ask the doctor to make sure on the frequency of giving the Percocet.
Decadron increases the control of N/V when use with Zofran and increase the appetite too by itself.
Please know that my personal opinion is not intended nor implied to be a substitute for professional medical advice. If provided, information are for educational purposes.Consult doctor is a MUST for changing of treatment plans.