Blood is mostly made up from water and so a good starting point is to eliminate dehydration, which of course can become
dangerous if not resolved. Make sure your Mother
is drinking plenty of fluids to keep her
blood pressure up and stable. When dehydration occurs the body does try to compensate by constricting blood vessels, increasing heart rate, but this can only work so much because when you need more oxygen for walking etc, the vessels must open again, dropping the pressure.