Final answer:
The best therapy for a patient admitted with symptoms of a vitamin B deficiency and suspected megaloblastic anemia is 'a. IM cyanocobalamin and folic acid', which addresses both the vitamin B12 and folate deficiencies.
Step-by-step explanation:
A patient with vitamin B deficiency experiencing symptoms such as hypoxia, anemia, numbness of hands and feet, and oral stomatitis is most likely suffering from megaloblastic anemia, which typically involves a deficiency of vitamin B12 and/or folate.
Among the treatment options provided, the most appropriate one, considering these deficiencies would be IM cyanocobalamin (an injectable form of Vitamin B12) and folic acid which addresses both the vitamin B12 and folate deficiencies. Therefore the correct answer to the therapy the nurse expects the prescriber to order would be 'a. IM cyanocobalamin and folic acid'.