The real question is, who the fuck killed CJ's mom?!
If I remember right Big Smoke was threaten by Tenpenny and Pulaski to get Sweet killed, Big Smoke then managed to convince Ryder and get him by his side and hired some BaLLaS to do the dirty job, Sweet wasn't home when the attack happened and CJ's mom got shot by the drive-by. Don't remember all the details behind it but pretty sure this is what happened, perhaps there's more clues in this video: