**Core Concept**
The question tests the student's understanding of a rare bleeding disorder characterized by a deficiency in a key protein necessary for blood clotting. This condition often presents with mucocutaneous bleeding symptoms, including frequent nosebleeds and easy bruising.

**Why the Correct Answer is Right**
The condition is caused by a deficiency in von Willebrand factor (VWF), a protein that plays a crucial role in platelet adhesion and aggregation. VWF also serves as a carrier for factor VIII, another essential protein in the coagulation cascade. Without sufficient VWF, the body's ability to form clots is impaired, leading to prolonged bleeding episodes. The patient's symptoms, including frequent nasal bleed and mild anaemia (Hb-6 mg%), are consistent with this diagnosis.

**Why Each Wrong Option is Incorrect**
**Option A:** This option might be a distractor for conditions that present with more severe bleeding symptoms, such as haemophilia A or B, which are caused by deficiencies in factors VIII and IX, respectively. However, these conditions typically present with more significant bleeding episodes, such as joint or muscle haemorrhages.

**Option B:** This option might be a distractor for conditions that present with easy bruising, such as platelet disorders or vitamin C deficiency. However, these conditions typically do not present with mucocutaneous bleeding symptoms, such as frequent nosebleeds.

**Option C:** This option might be a distractor for conditions that present with anaemia, such as iron deficiency or thalassemia. However, these conditions do not typically present with mucocutaneous bleeding symptoms.

**Clinical Pearl / High-Yield Fact**
Mucocutaneous bleeding symptoms, including frequent nosebleeds, are a hallmark of von Willebrand disease. This condition is often inherited in an autosomal dominant pattern, and patients may require regular infusions of VWF concentrate to manage their symptoms.

**Correct Answer:** B. von Willebrand disease.