PerhapsLove.....God bless grandmothers!
One thing that I noticed.....she "went to a meeting and got some numbers".....I could be wrong, of course, but, I get the impression that she was new to the group and, maybe, has not been going to AA on a regular basis.
Not working a regular program can lay the groundwork for relapse......
If she has not committed to really working a program of recovery....and getting a sponsor, and working the steps..etc.....I would take that into consideration when you are thinking about how soon she can have her son back....
I DO realize that you have no legal right to him, right now.....but, she may let you keep him for a while and not push the issue under the circumstances.....
These are only my thoughts and suggestions.....if they can be of any use for you.....
dandylion