Final answer:
The patient who received insulin at 8:30 pm should be monitored for hypoglycemia between 10:30 pm and 11:30 pm, which are the peak action times for regular insulin.
Step-by-step explanation:
The nurse should monitor the patient for signs of hypoglycemia primarily between the peak action times of regular insulin, which typically occurs between 2 to 4 hours after administration. Therefore, the appropriate time to monitor this patient, who received 10 units of regular insulin subcutaneously at 8:30 pm, would be option B: 10:30 pm to 11:30 pm. It is during this time that insulin's effect is the strongest, and the risk for hypoglycemia is highest. However, it is also important to continue to monitor the patient beyond this period, as individual responses to insulin can vary and hypoglycemia can still occur.