Does eating beef broth or soup made from beef bones causes mad cow disease?

No. The agent of MCD is found in the nerves/brain of the infected animal & could be on bones if the slaughtering process mixed the material together. That said, since the MCD surveillance started the risk of the disease is somewhat like the lottery in reverse. If you had ten million chances to win and only1 of 10mil to loose, would you worry about losing. I note only 1 case reported in the US in 2003.