If my Mom accidentally took Ibuprofen (200mg) with Advil (300mg) for her migraine, instead of Tylenol (acetaminophen) with Advil, is this an emergency?

No she'll be fine. The recommended dose of ibuprofen (sold as Advil and Motrin) is 10mg per kilogram every eight hours. If your Mom weighs 60kg (132 lbs) she could safely take 600mg every eight hrs or 1800mg/day. The biggest problems with ibuprofen are irritation of the stomach lining (even bleeding), decreased blood flow to kidneys, and a higher incidence of heart attacks. All of greatest concern in the elderly.