**Core Concept**
The patient's symptoms indicate a neurological or psychiatric complication arising from syphilis treatment, likely involving an adverse reaction to a specific medication.

**Why the Correct Answer is Right**
Hoigne Syndrome, also known as Neurosyphilis or Syphilis-induced psychosis, is a rare but severe complication of syphilis treatment, particularly with penicillin. It occurs in patients who have not received adequate treatment for their primary syphilis, leading to the development of neurosyphilis. The patient's symptoms, such as mental confusion, hallucinations, and fear of impending death, are consistent with this diagnosis. The syndrome is thought to be caused by the breakdown of the blood-brain barrier, allowing the syphilis spirochete to infect the central nervous system.

**Why Each Wrong Option is Incorrect**
**Option A:** The Jarisch-Herxheimer Reaction is a common reaction to syphilis treatment, characterized by fever, headache, and muscle aches. However, it does not typically involve psychiatric symptoms or visual hallucinations.

**Option C:** Undiagnosed psychosis is a possible explanation for the patient's symptoms, but it does not account for the specific relationship between the symptoms and the recent syphilis treatment.

**Option D:** Schizophrenia is a chronic mental health disorder characterized by hallucinations, delusions, and disorganized thinking. However, it is not typically associated with the patient's recent history of syphilis treatment or the specific constellation of symptoms described.

**Clinical Pearl / High-Yield Fact**
When treating patients with syphilis, it is essential to carefully assess their neurological status and consider the possibility of neurosyphilis, even in the absence of typical symptoms. A high index of suspicion and prompt diagnosis can help prevent severe complications, including Hoigne Syndrome.

**✓ Correct Answer: B. Hoigne Syndrome**