You can give her Tab Domcolic 10 mg three times a day ( maximum) till vomiting stops. Along with that tab Pantocid 1 tab in the morning on empty stomach for 3 days. Give ORS solution to maintain fluid levels in the body.
Next Steps
If vomiting doesn't stop and if it is associated with stomach ache you need to consult a surgeon to rule out appendicitis etc...
Health Tips
Take the medication , maintain fluid levels and consult a physician or surgeon immediately if the condition worsens.