**Core Concept**
The patient's symptoms, including painful weeping rashes and acute punctate keratopathy, suggest a diagnosis related to the ocular surface and skin. This presentation, in the context of a history of chemotherapy for Non-Hodgkin's lymphoma, raises the possibility of a paraneoplastic syndrome.

**Why the Correct Answer is Right**
The patient's symptoms and history are consistent with a diagnosis of **Mucous Membrane Pemphigoid (MMP)**. MMP is a paraneoplastic syndrome that typically presents with painful oral and ocular lesions, including weeping rashes and acute punctate keratopathy. The disease is thought to be caused by the production of autoantibodies against the basement membrane zone of the mucous membranes, leading to blistering and erosion. In this case, the patient's history of chemotherapy for Non-Hodgkin's lymphoma suggests that the underlying cancer may be triggering the autoimmune response.

**Why Each Wrong Option is Incorrect**

* **Option A:** This option is not relevant to the patient's symptoms and history.
* **Option B:** While this option may be a consideration in the differential diagnosis, it is not the most likely diagnosis given the patient's history of chemotherapy and the specific symptoms presented.
* **Option D:** This option is not consistent with the patient's symptoms and history.

**Clinical Pearl / High-Yield Fact**
Mucous Membrane Pemphigoid is a rare paraneoplastic syndrome that can present with a range of symptoms, including painful oral and ocular lesions. It is often associated with underlying cancers, including lymphomas, and can be triggered by chemotherapy.

**Correct Answer:** C. Mucous Membrane Pemphigoid