What have you found to be the quickest and most effective way to shut down a crazy pro per party who is threatening civil litigation against everyone and their mother?

First, there is no guarantee that she will go away no matter how you approach her.  In some cases, a pro se will go away if you ignore him/her. In others, it makes them more aggressive. And vice versa–aggressive response could make them go away, or could make them into a self righteous crusader.

Second, don’t assume that she is stupid.  Occasionally the pro per plaintiff can be cunning and clever enough to drag things out for years.

Third, Courts here in the DMV will give the pro per the opportunity of correcting procedural and substantive errors that they would not have done with lawyers.  Bottom line: you could be litigating with her for a long time.

There are 2 general theories of how to deal with pro per parties. One is to push back hard.  File Motions to dismiss, fight inappropriate discovery, and don’t get sucked into fights over trivia.  In case of doubt, bury them in paper.  Get your Motion for Summary Judgment.  If necessary, file for sanctions.  Alternatively there is what a friend calls the tit-for-tat method.  He call it the “reasonable gets reasonable” approach.  You show you can be reasonable by making a reasonable (not final) set of concessions and offers.  Then indicate that reasonable response is in hope that she will respond reasonably.  If she is reasonable in response, then respond favorably.  But if she is unreasonable, you take away some of your “reasonable” offer.