Violetfire ~~ Even though your husband has talked with her and even though it seems she realizes (at least to some extent) that she had ventured waaaaay past any kind of reasonable boundary lines, I'd still make sure I kept hard copies of those emails and also keep those "grandparents' rights" clippings stashed away somewhere in an envelope just in case another event arises in the future and she begins threatening again. You'll want and need to have a paper trail of all of this. In addition, please write down the date she visited your house with strangers and tried to 'convert' your husband away from his chosen profession.
Hopefully all the stuff can be shoved into a big envelope and stuck at the end of the top shelf of your closet never to be referenced again. But for your own and your husband's peace of mind, you need to know that you have it there ... just in case.