**Core Concept**
The patient's symptoms are likely indicative of a vaginal yeast infection, caused by an overgrowth of Candida albicans. This condition is characterized by a thick, curdy-white discharge and is often accompanied by itching and vaginal irritation.

**Why the Correct Answer is Right**
The correct treatment for a vaginal yeast infection is a topical antifungal agent, such as clotrimazole or fluconazole. These medications work by inhibiting the synthesis of ergosterol, an essential component of the fungal cell membrane. This leads to the disruption of the cell membrane and ultimately the death of the fungal cells.

**Why Each Wrong Option is Incorrect**
**Option A:** Metronidazole is an antibiotic that is used to treat bacterial vaginosis and trichomoniasis, not yeast infections.
**Option B:** Doxycycline is an antibiotic that is used to treat bacterial infections, not fungal infections.
**Option C:** The patient's symptoms do not indicate a need for hormonal therapy, such as estrogen replacement.

**Clinical Pearl / High-Yield Fact**
It's essential to differentiate between vaginal yeast infections and bacterial vaginosis, as the treatments are distinct. Yeast infections are often associated with a thick, white discharge, while bacterial vaginosis is characterized by a thin, grayish discharge with a fishy odor.

**Correct Answer:** C.