Please help! My boss is being thrown into madness!

Ok, I don't want to whine or nit-pick or even micro manage ANYONE. I can barely manage my own life. But, there is a friend/ex-caregiver that came to visit my boss on my day off. This woman is nice enough. But, she has some really crazy ideas, and lots of government conspiracy theories. She fills my bosses head with crazy things like the government puts chemicals in baby wipes to intentionally kill babies and cause cancer, the reason why plastic is produced is to keep pets, and people within the quota of population control, etc. the one influence she has over my boss is convincing her that the doctors meds are designed to exterminate her. The woman has the answer though. She has convinced my boss that she has the secret to all cures, and longevity through the various therapeutic oils she recommends, (and makes a hefty commission from selling them). We already went through this entire matter about two years ago, and my boss had a lot more capacity back then, and ended up firing her because of the way she treated her. She has a bad habit of reeking nothing but chaos in an otherwise very peaceful, and yes boring household. I told my boss that if she gets involved with this nutty woman again, and refuses to take her meds again, I can't work for her anymore. But, I don't know if that was a very smart thing to say. My boss is convinced that FRANKENSCENT is going to keep her alive...which this woman happens to sell at $45.00 a 1 ounce bottle. She has my boss believing all kinds of crazy stuff. How can I prevent this woman from taking advantage of my bosses vulnerability? She's not breaking the law. But, she is certain inn getting the tea cups rattling around here....just when everything was all settled down, and in order the way boss wanted it.