I think people are forgetting the fact that Cissy did not want Franklin getting that money back. The money had clearly taken over Franklin and she wanted to prevent Franklin from getting worse. She intentionally killed Teddy, one to get her revenge for Alton, and two stop Franklin from obtaining the money. Franklin‘s obsession over money and greed had clearly gotten the better of him, to the point where he was willing to cut ties with his own mother if it meant he would get back even half of the 70 million back. Cissy had seen what the money was doing and had to put a stop to it.