I'm so sorry for your lossIt's always hard losing a pet, even worse when you have to watch it suffer...
I have to ask though, what size mice were you feeding her? And how do you thaw them?
It sounds like the mouse was rotting in her stomach before the regurge, which could be caused by several things including but not limited to feeding oversized prey, letting the mouse sit at room temp or in warm water for too long (thus allowing it to "go bad"), having it go bad then refreezing (which usually happens before you buy and is relatively out of your control), or even not thawing it enough. All of this assuming you feed f/t. It could also be caused by internal defects of the snake but that tends to be rarer than human error.
Also im confused; you found TWO regurgitated mice in her cage? One old and dried and one from last Monday?
I really am sorry for your lossand I'm sorry if the bombardment of questions takes the sensitivity out of my condolences. I think I speak for most of us when I say we're just trying to solve the puzzle of why, for the sake of the baby and to help you find peace over it, as well as to educate ourselves and any others who may find this thread in the future.