70 yr dad has all normal CBC except MCV 102, hemoglobin 9.5 and hematocrit 29 and RBC 2.8 mil. Liver, vitamns, WBC are normal. Why anemia? Leukemia?

Anemia? cause. Your dad has anemia which is significant and needs complete medical evaluation by his pcp. He should go see his doctor right away as he is at risk for GI blood loss(check for colon cancer) or problems in making blood either due to vitamin B12 deficiency(high MCV is pointing to this possibility) and also check the bone marrow to make sure he does not have mds(problem in making blood cells).
See hematologist. He has macrocytic anemia- there are different conditions can cause this anemia- from vitamin deficiency, liver problem, thyroid problem, breaking down of red blood cells to problem with his bone marrow. He should ask his pmd to refer him to see a hematologist for further work-up. A bone marrow biopsy would likely need to be done to rule out mds-myelodysplastic syndrome-which is a preleukemic state.