**Core Concept**
Elderly women experiencing recurrent vulvar swelling and pain are likely suffering from a condition characterized by chronic inflammation of the vulvar skin and mucous membranes. This condition is often associated with human papillomavirus (HPV) infection and can be exacerbated by hormonal changes during menopause.

**Why the Correct Answer is Right**
The correct diagnosis is lichen sclerosus, a chronic autoimmune inflammatory condition that affects the vulvar skin and mucous membranes. Lichen sclerosus is more common in postmenopausal women and can cause significant discomfort and pain. The condition is characterized by the presence of white, atrophic patches on the vulvar skin, which can lead to scarring and narrowing of the vaginal opening.

**Why Each Wrong Option is Incorrect**
**Option A:** Vulvodynia is a condition characterized by chronic vulvar pain, but it does not typically present with swelling and is not directly associated with HPV infection.
**Option B:** Vulvar intraepithelial neoplasia (VIN) is a precancerous condition that can cause vulvar pain and swelling, but it is not typically associated with the chronic inflammation and scarring seen in lichen sclerosus.
**Option C:** Vulvar cancer is a rare condition that can cause vulvar pain and swelling, but it is not typically associated with the chronic inflammation and scarring seen in lichen sclerosus.

**Clinical Pearl / High-Yield Fact**
Lichen sclerosus is a chronic condition that requires long-term management, and prompt diagnosis is essential to prevent scarring and narrowing of the vaginal opening.

**Correct Answer:** C.