My fault ?

[bright sparks]

I would definitly address it if it is an ongoing thing. She needs to stop making this snidey comments and come out with it and then move on. This cold and flu season has been particularly bad and it is not uncommon for children to be ill with a cold all year sometimes. It sucks that the kids feel crumby but its reality and blame is not helpful and really unless you purposely infect someone, which really who does, then it is nobodies fault that her children are sick, it just simply is what it is. If she says anything again I would take that opportunity to just say that it is what it is and its not nice to see any of the dckids ill but that you are feeding the healthy fruits and vegs in the hope to knock this cold out and before soon spring and summer will be hear. If she goes on with herself I would just make a comment along the lines of how it sounds like she blames you for their illness, and see what her comeback is to that.