Foster Kitten Died from Anesthesia?

That is pretty messed up. Sometimes animals just have bad reactions to anesthesia, it's nobody's fault because no one can predict it. I'm not sure why the lady in charge blames you guys because things happen and she should know that. She should be willing to let you guys adopt the white kitty, usually fosters have first dibs on adopting their foster pet. She is cheating a kitten out of a home because she's upset about what happened with the black kitten and that's not right and is unprofessional. Tell her that what happened was not your fault and you want to know why you can't adopt the white kitten. If she doesn't give you a good answer, I would report her to someone above her at the shelter and if that doesn't work, then I would suggest fostering cats at another shelter, where people are more professional at their job.