Miss me with all that. Lady is ill to the point she can even get out the bed and he's physically abusing her? This is like a kid who is getting raped by his uncle asking his family not to have him arrested because that's his favorite uncle that he loves to death. You gonna respect the kids wishes too?
I am giving you a possible why for their actions. Why they did not jail him and why they did not kill him. I am not there, I do not know what actually happened, but I can make a guess based on how mothers can be when it comes to their children. It is quite possible that she begged them not to hurt him or put him in jail, because I have seen over my life time mothers make that same request over and over again for their children.
No where in my statement did I support the outcome and I in fact would have preferred them place him in jail and he suffer the consequences of being there as an abuser. Still, I can make a guess on why they did not do that, and the most logical guess is because the mother asked, or perhaps even begged, them to not do it.