**Core Concept**
The patient is likely experiencing a normal grief response following the loss of her husband, but her belief that she saw him walking down the street yesterday suggests the presence of a hallucination, which may be indicative of a more complex psychiatric condition, such as Brief Psychotic Disorder (BPD) or Major Depressive Disorder with psychotic features.

**Why the Correct Answer is Right**
The patient's symptoms, including crying, difficulty sleeping, and hallucinations, are suggestive of a depressive disorder with psychotic features. The physician should first assess the patient's mental status to determine the nature and severity of her symptoms. The physician should also consider the possibility of a Brief Psychotic Disorder, which is characterized by the sudden onset of psychotic symptoms (e.g., hallucinations, delusions) in the context of a significant stressor, such as the loss of a loved one.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not address the patient's hallucinations or the need for a comprehensive psychiatric evaluation.
**Option B:** This option is incorrect because it does not provide a clear plan for managing the patient's symptoms, including her hallucinations.
**Option C:** This option is incorrect because it may not be the most appropriate first step in managing the patient's symptoms, and it does not address the need for a comprehensive psychiatric evaluation.

**Clinical Pearl / High-Yield Fact**
In patients experiencing a significant stressor, such as the loss of a loved one, it is essential to assess for the presence of psychotic symptoms, such as hallucinations or delusions, which may indicate a more complex psychiatric condition.

**Correct Answer: C. Order a comprehensive psychiatric evaluation and consider a referral to a psychiatrist.**