**Core Concept**
Meningitis is an inflammatory condition of the protective membranes covering the brain and spinal cord, known as the meninges. This inflammation can be caused by infection, typically bacterial, viral, or fungal, leading to various complications in children.

**Why the Correct Answer is Right**
The complications of meningitis in children are multifaceted and include long-term neurological sequelae such as hearing loss, cognitive impairment, and seizures. One of the most significant complications is hydrocephalus, a condition characterized by an accumulation of cerebrospinal fluid (CSF) in the brain, leading to increased intracranial pressure. This occurs due to impaired CSF absorption by the arachnoid villi, often secondary to inflammation and scarring of the meninges.

**Why Each Wrong Option is Incorrect**
**Option A:** Hydrophobia is a symptom of rabies, not a complication of meningitis.
**Option B:** Encephalitis is a separate condition characterized by inflammation of the brain parenchyma, although it can be a complication of meningitis.
**Option C:** Meningoencephalitis is a condition that involves both meningitis and encephalitis, but it is not a complication of meningitis.

**Clinical Pearl / High-Yield Fact**
It is essential to recognize that the type of pathogen causing meningitis can influence the risk of complications. For example, Haemophilus influenzae type b (Hib) meningitis, which was common in the pre-vaccine era, carries a higher risk of long-term neurological sequelae compared to Streptococcus pneumoniae meningitis.

**Correct Answer:** D. Hydrocephalus