The symptoms you have described of bluish discoloration, swollen feet, and visible blood pooling in the veins could indicate several conditions. Some of the main differentials would Deep Vein Thrombosis (DVT) involves a blood clot in deep veins that can block circulation, while Chronic Venous Insufficiency (CVI) results from faulty vein valves causing blood to pool. Peripheral Artery Disease (PAD) involves narrowed arteries reducing blood flow to the legs, and heart failure can lead to fluid buildup and leg swelling. Other possibilities include lymphedema, a lymphatic system issue causing persistent swelling, or thrombophlebitis, inflammation of veins due to clots.
We need to make sure (through physical examination and medical review) that this is not DVT as there is a risk of blood clot travelling to the lung which can be life threatening. Have you noticed any pain in the calves ? Is your mother on any blood thinners ? How long has she had these symptoms?