Mommy could also be dealing with some of the residual effects of having her head smashed in and serious injury to her brain. I mean I don't think it's too outrageous to posit that perhaps the area of her brain that helps with reasoning, and logic may have been permanently altered in the attack. Maybe her brain is just not functioning at full capacity. When you combine that with the natural instinct (most) mother's have to protect their children you have a pretty powerful proclivity toward her denying his involvement. I don't know...just a thought.