Final answer:
The most important intervention is to monitor vital signs closely, as it allows for the management and early detection of potential complications in a patient with GI bleeding and pancreatitis.
Step-by-step explanation:
The most important intervention for a nurse to implement for a patient with a history of alcohol abuse admitted for GI bleeding and pancreatitis is b. Monitor vital signs closely. This is crucial because the patient's condition may rapidly change and the severity of their symptoms—including hypertension and potential for further complications needs to be closely observed. Monitoring vital signs will help manage and detect complications like shock, organ failure, or further bleeding, allowing for timely interventions to prevent deterioration of the patient's condition. Administering pain medication may also be important but is secondary to vital sign monitoring. Providing a meal may not be appropriate given the patient's current GI condition, and encouraging alcohol consumption is contraindicated and could exacerbate the patient's condition.