**Core Concept**
The patient's presentation of fever, malaise, hilar lymphadenopathy, and hypercalcemia suggests a diagnosis of sarcoidosis, a systemic granulomatous disease characterized by the formation of non-caseating granulomas in various organs, including the lungs and lymph nodes.

**Why the Correct Answer is Right**
The correct answer is related to the histopathological findings in sarcoidosis. Sarcoidosis is characterized by the presence of non-caseating granulomas, which are collections of immune cells, including macrophages and T lymphocytes, that accumulate in response to an unknown antigen. These granulomas are typically found in the lungs, lymph nodes, and other organs, and are a hallmark of the disease. The presence of non-caseating granulomas in the biopsied lymph nodes would confirm the diagnosis of sarcoidosis.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it does not accurately describe the histopathological findings in sarcoidosis. Sarcoidosis is characterized by non-caseating granulomas, not caseating granulomas.
* **Option B:** This option is incorrect because it suggests a different diagnosis, such as tuberculosis, which is characterized by caseating granulomas, not non-caseating granulomas.
* **Option C:** This option is incorrect because it suggests a different diagnosis, such as lymphoma, which is characterized by the proliferation of malignant lymphocytes, not non-caseating granulomas.

**Clinical Pearl / High-Yield Fact**
Sarcoidosis is a systemic disease that can affect multiple organs, including the lungs, lymph nodes, skin, and eyes. It is characterized by the formation of non-caseating granulomas, which can lead to a range of symptoms, including fever, malaise, and hypercalcemia. A high index of suspicion is necessary for diagnosis, as the symptoms can be nonspecific and the disease can mimic other conditions.

**Correct Answer: C. Non-caseating granulomas**