**Core Concept**
The patient's presentation of bilateral sixth nerve palsy and an ataxic gait suggests a diagnosis of Wernicke's encephalopathy, a neurological disorder caused by thiamine (vitamin B1) deficiency. This condition is often seen in individuals with chronic alcoholism or malnutrition.

**Why the Correct Answer is Right**
Wernicke's encephalopathy is a medical emergency that requires prompt treatment with thiamine to prevent progression to Korsakoff's syndrome. The patient's symptoms are due to the toxic effects of thiamine deficiency on the brain, particularly the thalamus and mammillary bodies. Administration of thiamine helps to replenish the body's stores and alleviate the symptoms of the disease. Thiamine is essential for the decarboxylation of alpha-keto acids in the Krebs cycle, and its deficiency leads to impaired energy production in the brain.

**Why Each Wrong Option is Incorrect**
**Option A:** Metronidazole is an antibiotic used to treat infections caused by anaerobic bacteria and protozoa, but it is not the appropriate treatment for Wernicke's encephalopathy.
**Option B:** Benzodiazepines may be used to manage symptoms of anxiety and insomnia but do not address the underlying cause of the patient's condition.
**Option C:** Steroids may be used to treat inflammatory conditions, but they are not indicated in the treatment of Wernicke's encephalopathy.

**Clinical Pearl / High-Yield Fact**
Wernicke's encephalopathy is a classic example of a treatable cause of confusion and ataxia, and prompt recognition and treatment can prevent long-term neurological damage. Remember the "CHICK" mnemonic to diagnose Wernicke's encephalopathy: Confusion, Hallucinations, Incoordination, Korsakoff's syndrome, and Cerebellar ataxia.

**Correct Answer:** C. Thiamine (vitamin B1)