**Core Concept**
The patient's symptoms suggest a diagnosis of scabies, a parasitic infestation caused by the mite Sarcoptes scabiei. The intense itching, especially at night, is characteristic of scabies.

**Why the Correct Answer is Right**
Topical permethrin cream is the first-line treatment for scabies. It works by disrupting the insecticidal target site of the nicotinic acetylcholine receptor (nAChR) in the mite's nervous system, ultimately leading to the death of the mite. Permethrin also has a low toxicity profile and is safe for use on infants and children.

**Why Each Wrong Option is Incorrect**
**Option A:** Sulfur ointment was once a treatment for scabies but is less effective and more irritating than permethrin.
**Option B:** Ivermectin is an oral antiparasitic medication used to treat scabies, but it's not the first-line topical treatment and has a higher risk of side effects.
**Option C:** Benzyl benzoate is an older treatment for scabies, but it's less effective and more irritating than permethrin.

**Clinical Pearl / High-Yield Fact**
When treating scabies, it's essential to treat all household members and close contacts simultaneously to prevent re-infestation.

**Correct Answer:** C. Permethrin cream.