**Core Concept**
Granulation tissue in the external ear, along with severe ear pain and facial palsy, suggests a possible otitis externa complication, specifically malignant otitis externa. This condition is characterized by necrotizing infection of the external auditory canal and surrounding tissues, often affecting diabetic patients.

**Why the Correct Answer is Right**
Malignant otitis externa is caused by Pseudomonas aeruginosa, which takes advantage of the compromised immune system in diabetic patients. The infection spreads to the cartilage and bone of the external auditory canal, leading to severe pain, granulation tissue formation, and facial nerve palsy due to the proximity of the facial nerve to the affected area. The facial nerve palsy is a result of the spread of infection to the temporoparietal fascia and the deep lobe of the parotid gland.

**Why Each Wrong Option is Incorrect**
**Option A:** Necrotizing otitis externa is a more common term for malignant otitis externa, but it is not the correct answer in this context.
**Option B:** While diabetic neuropathy can cause facial palsy, it does not explain the presence of granulation tissue in the external ear.
**Option C:** Cholesteatoma is a condition characterized by a skin cyst in the middle ear, which can cause ear pain and hearing loss, but it is not associated with granulation tissue or facial palsy in this context.

**Clinical Pearl / High-Yield Fact**
Malignant otitis externa is a medical emergency that requires prompt treatment with broad-spectrum antibiotics and surgical debridement. Early recognition and treatment can prevent serious complications, including facial paralysis and skull base osteomyelitis.

**Correct Answer:** C.