Final answer:
The most urgent assessment finding to report is 'The client reports episodes of melena,' as this indicates gastrointestinal bleeding, a serious complication of peptic ulcer disease that requires immediate medical attention.
Step-by-step explanation:
The student is asking which assessment finding should be reported immediately to the physician when a client is receiving H2-receptor antagonists for the treatment of peptic ulcer disease (PUD). Of the options provided, the most critical and urgent finding to report would be 'C. The client reports episodes of melena.' Melena refers to dark, tarry stools which are a sign of gastrointestinal bleeding, a potential complication of PUD. Bleeding ulcers can contribute to melena, and immediate assessment by a physician is essential to prevent complications such as anemia or shock from significant blood loss.