**Core Concept**
A mucocele of the gallbladder is a rare condition characterized by the accumulation of mucus within the gallbladder, often secondary to chronic gallbladder inflammation or obstruction. This condition can lead to gallbladder distension and potentially life-threatening complications such as gallbladder rupture or torsion.

**Why the Correct Answer is Right**
The treatment of choice for a mucocele of the gallbladder is surgical removal, typically involving open cholecystectomy or laparoscopic cholecystectomy. This is because surgical intervention can effectively prevent further complications and alleviate symptoms associated with the mucocele. Surgical management also allows for histopathological examination of the gallbladder to rule out malignancy, which is a potential risk in mucocele formation.

**Why Each Wrong Option is Incorrect**
**Option A:** Conservative management with antibiotics and supportive care is not sufficient for treating a mucocele of the gallbladder, as it does not address the underlying cause of the condition and may lead to further complications.
**Option B:** Endoscopic retrograde cholangiopancreatography (ERCP) may be used to relieve obstruction in some cases, but it is not the primary treatment for a mucocele of the gallbladder.
**Option C:** Cholecystostomy may provide temporary relief by draining the mucocele, but it does not address the underlying cause of the condition and may lead to recurrent mucocele formation.

**Clinical Pearl / High-Yield Fact**
It is essential for clinicians to recognize the potential for malignancy in patients presenting with a mucocele of the gallbladder and to consider surgical intervention to prevent further complications.

**Correct Answer:** C.