What is a severe complication of otalgia and facial nerve palsy in a diabetic?

Malignant otitis externa is indeed a severe complication that can arise in a diabetic patient who presents with otalgia (ear pain) and facial nerve palsy. It is a serious infection of the external ear canal, typically caused by Pseudomonas aeruginosa, that can extend to involve surrounding structures, including the skull base. Diabetes mellitus, especially when poorly controlled, increases susceptibility to infections and can lead to more severe forms of otitis externa. The presence of facial nerve palsy suggests a significant involvement of the surrounding tissues, which is consistent with the complications seen in malignant otitis externa.

The other conditions listed do not reflect the combination of symptoms as relevantly as malignant otitis externa does. Bell's palsy primarily pertains to unilateral facial nerve impairment and is not directly associated with the ear or as severe. Diabetic neuropathy involves nerve damage due to high blood sugar levels but does not explain the acute presentation alongside otalgia. Acute otitis media, while also a potential ear infection, would not typically cause facial nerve palsy unless there is a more severe complication present, which aligns closely with malignant otitis externa. Thus, the severe nature of malignant otitis externa in the context of these symptoms makes it the correct choice.