Final answer:
Vitamin D is the vitamin that would be helpful in the treatment of the patient's disease. It is essential for bone health, calcium absorption, and general immunity against infections.
Step-by-step explanation:
Vitamin D would be helpful in the treatment of the patient's disease. Vitamin D is essential for bone health and plays a role in calcium absorption. In addition, it is also important for general immunity against infections. Therefore, supplementing with vitamin D can help improve the patient's bone pains, frequent infections, and bleeding symptoms.