Man, I can't believe the amount of stress this is causing.
As DMs, one of our greatest talents is our ability to think extemporaneously. In short, this means to think ahead into possibilities that haven't happened yet. I assume that, after X amount of years of DMing, one should have honed this talent to some kind of edge.
What is the motivation of Madame Eva? To tell the PCs things to aid them in concluding the adventure. Why? To help the PCs conclude the adventure. She's an NPC in a module; back in the 1e days, this meant that she was either there to help you or try and kill you. Is is that hard to call a spade a spade and accept the NPC at face value? And if not... do you NEED WotC to hand-feed you every possible scenario for every little- to no-consequence NPC in their supplements?
What happens at the end? You tell me... it's YOUR campaign world. If you're running this module as a stand-alone play-'til-its-over adventure, you kill the bad guy and it's over. Yay. If you're adding this into your campaign world, how does the killing the bad guy affect your world, or does it at all? Again, all up to you, as the DM.
I just don't understand all the confusion... plug-n-play modules must be a foreign concept to today's d20 gamers...