The idea of AG's of visiting NM to ask why he did what he did and what exactly happened. I don't think it's possible to understand the way a sick, twisted mind works. No explanation is going to comfort her or the rest of Becky's family I don't think.
I don't think NM would disclose the sordid events surrounding BW'S death. Not to his Mom. In any case. He'd be worried enough already that his Mom will reject him. And that is the direct opposite of why he had to rid BW from his Mom. That's why he's already written a note to her from HMP Bristol. In the added hope he'll get a reply. Something physical he can get from his Mom that he can read over and over again.
Whether AG replies to him that's a hard one to answer. He's her son. But if she's feeling physically nauseous over him taking a family members' life. Then he will have to accept her wishes. As she is married to the father of BW. Surely her loyalty should be with him.
Tough call. Not one I'd like to be in. .