What is the best midecin for high blood pressure for age above 50?

Depends. There are many good options for whatever age. The right medicine is determined by what is causing the high blood pressure, how high it is, other meds you are taking, and insurance coverage, and other factors.
Blood pressure. Each blood pressure medication acts on specific receptors in your body, it is not a one medication fits all, usually there is a first line therapy , a second and third line therapy , depending on the extent of the blood pressure.