What Can I Give A Miniature Dachshund, To Calm Random

what can I give a miniature dachshund, to calm random aggressive behavior, It is my mothers dog and is aggressive when she doesn't get her way and the dog is very stubborn and does seem to learn that this behavior will not be tolerated, the dog is now 9 years old and it has been an ongoing problem since she was a pup. Iy is at the point now where my mother is going to give up. what can we do?