is it normal that the blood pressure of my mom is 151/79 mmHg Thnx?

No. American College of Cardiology guidelines recommend BP be 130/80 mmHg or less. That is ideal. If your systolic BP is 151 mmHg, first it ought to be confirmed by multiple measurements over several days; and then second, lifestyle changes is next. Restrict salt intake to less than 2000 mg/day, walk four times/week atleast briskly, quit tobacco use to ensure heart healthy lifestyle.