Final answer:
The patient should be admitted to the hospital and treated with IV ceftriaxone, as her symptoms are consistent with Rocky Mountain Spotted Fever, a serious and potentially fatal condition if untreated.
Step-by-step explanation:
A 16-year-old girl presenting with a fever and a petechial rash over her ankles and palms in North Carolina, after possibly being bitten by a tick, is suggestive of Rocky Mountain Spotted Fever (RMSF). The next step in management, after recognizing the signs and symptoms consistent with a tickborne rickettsial disease, would be admitting the patient to the hospital and ordering IV ceftriaxone (Option B). Early treatment is critical for RMSF as it can be fatal if left untreated; specifically, one should not wait for the appearance of petechiae to initiate treatment, as this can be a sign of progression to severe disease. Doxycycline is also an appropriate treatment for RMSF, especially in non-pregnant patients, and could be considered as an alternative to ceftriaxone.