What Causes Nose Bleeding With High Blood Pressure?

Hi. I'm from Malaysia. it's about my mother. she is asian. she is 62 years old. height about 158cm. weight about 45kg. she has high blood pressure. her blood pressure is about 168. About a week ago, she has bloody nose. it happen early in the morning and night. she don't feel any pain or sign before it happen. sometimes it also happen when she do heavy housework. she already go to hospital but the doctor just ask her to reduce eating salty food and give her vitamin. Please help my mother.