Does taking glucosamine chondroitin help to fortify bone density in elderly people?

No. This product is supposed to "loosen your joints" but it will not do anything to your bone density. Calcium and vitamin d are some supplements that can help with your bone.
No. Glucosamine and chondroitin are components of cartilage and have no relationship to bone metabolism or denisty. So no, they will have no effect.