Final answer:
The 50-year-old patient with an unresponsive pupil requires the most immediate assessment, as this can indicate serious intracranial pressure.
Step-by-step explanation:
After the emergency department nurse has received a status report on patients admitted with head injuries, the patient who should be assessed first is the 50-year-old patient whose right pupil is 10 mm and unresponsive to light. This is a sign of potential intracranial pressure which can be life-threatening and requires immediate attention. A rapid assessment of neurological function is crucial in an emergency situation to identify life-threatening conditions, provide prompt treatment and improve the chances of recovery. The other patients, while they do have head injuries, do not present with signs that are as immediately concerning as an unresponsive pupil, which indicates a potential compression of cranial nerves or brainstem.