Final answer:
The most important assessment for a nurse when a patient presents with nausea and vomiting after a seaside resort visit should be to understand the patient's typical meal pattern to determine if they consumed contaminated food or water.
Step-by-step explanation:
The patient's symptoms of nausea and vomiting after a visit to a seaside resort could be indicative of a variety of health issues, such as food poisoning, viral illnesses like norovirus, or even sunstroke.
The most important assessment would likely be to understand her typical meal pattern, as it will help determine if the patient consumed any contaminated food or water, which is a common cause of gastrointestinal distress in travelers. It's also important to consider other potential contributing factors, such as sun exposure, but diet-related reasons are often the primary cause of acute gastrointestinal symptoms in a travel context.