**Core Concept**
Vidian neurectomy is a surgical procedure involving the resection of the vidian nerve, a branch of the nervus intermedius that supplies the lacrimal gland and the nasal mucosa. This procedure is aimed at reducing excessive nasal secretion and rhinorrhea, often seen in conditions like rhinitis or nasal polyps.

**Why the Correct Answer is Right**
The vidian nerve carries parasympathetic fibers that stimulate the nasal mucosa to produce mucus. By interrupting these fibers through neurectomy, the procedure reduces the production of nasal secretions. This is particularly useful in patients with chronic rhinitis or nasal polyps who experience significant nasal congestion and rhinorrhea.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because vidian neurectomy is not typically performed for epistaxis (nosebleeds). While nasal mucosa is involved in epistaxis, the procedure targets excessive nasal secretion, not bleeding.
**Option B:** This option is incorrect because vidian neurectomy is not a treatment for nasal tumors or malignancies. The procedure is focused on reducing nasal secretion, not addressing neoplastic growths.
**Option C:** This option is incorrect because vidian neurectomy is not a procedure for improving nasal airflow or correcting nasal obstruction. While it may have some indirect benefits, the primary goal is to reduce nasal secretion.

**Clinical Pearl / High-Yield Fact**
The vidian nerve is a branch of the nervus intermedius, which also supplies the lacrimal gland. This anatomical correlation is important to remember when considering the role of parasympathetic innervation in the lacrimal gland's function.

**Correct Answer:** C.