**Core Concept**
The patient's presentation of gradual hearing loss and intermittent tinnitus, in conjunction with the MRI findings of an extra-axial tumor in the cerebellopontine angle (CPA), suggests a diagnosis related to the cranial nerves, particularly the vestibulocochlear nerve (CN VIII), which is responsible for transmitting sound and balance information.

**Why the Correct Answer is Right**
The presence of a tumor in the CPA region is highly suggestive of an acoustic neuroma, also known as a vestibular schwannoma. This type of tumor arises from the Schwann cells of the vestibulocochlear nerve and can cause compression of the nerve, leading to symptoms such as hearing loss, tinnitus, and balance problems. The tumor is typically slow-growing and can be managed with surgical resection or stereotactic radiosurgery.

**Why Each Wrong Option is Incorrect**
**Option A:** A meningioma is a type of extra-axial tumor that can occur in the CPA region, but it is more commonly associated with compression of the trigeminal nerve (CN V) and less frequently with vestibulocochlear nerve symptoms.
**Option B:** A glioma is a type of primary brain tumor that arises from glial cells, but it is less likely to present in the CPA region and more commonly associated with other cranial nerve deficits.
**Option C:** A metastatic tumor to the brain is a possibility in a 63-year-old patient, but the presentation would typically be more rapid and associated with other systemic symptoms, as well as more widespread brain involvement.

**Clinical Pearl / High-Yield Fact**
The cerebellopontine angle is a critical region where several cranial nerves converge, and tumors in this area can cause a range of symptoms depending on the nerve involved. A high index of suspicion for acoustic neuroma should be maintained in patients presenting with hearing loss, tinnitus, and balance problems, especially if there are no other systemic symptoms.

**Correct Answer:** C.