**Core Concept**
The patient is presenting with symptoms of a psychotic disorder, specifically delusions of guilt and nihilistic delusions. This is a classic manifestation of a severe depressive episode with psychotic features or a diagnosis of a delusional disorder.

**Why the Correct Answer is Right**
The patient's symptoms suggest a severe depressive episode with psychotic features, which requires a comprehensive treatment plan. Antidepressants, such as selective serotonin reuptake inhibitors (SSRIs), can help alleviate depressive symptoms. Antipsychotics, such as risperidone or olanzapine, can help manage psychotic symptoms. Electroconvulsive therapy (ECT) may also be considered in severe cases. A comprehensive treatment plan should include psychotherapy, such as cognitive-behavioral therapy (CBT), to address underlying emotional and psychological issues.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because this option does not address the patient's psychotic symptoms, which are a significant component of his presentation.
**Option B:** Incorrect because this option may be harmful and is not a recommended treatment for a patient with a severe depressive episode with psychotic features.
**Option C:** Incorrect because this option may not be sufficient to address the patient's complex symptoms and underlying psychological issues.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that patients with psychotic symptoms require a comprehensive treatment plan that includes a combination of pharmacological and psychotherapeutic interventions. Antipsychotics can be used as a first-line treatment for psychotic symptoms, but they should be used in conjunction with antidepressants and psychotherapy.

**Correct Answer: A. Refer him to a psychiatrist for comprehensive treatment.**