How to deal with a negative mother in law?

You need to just talk to her and tell her how you feel. Cause you only have one life and you should have your parents in your life. Explain your not attacking her, you just don't feel comfortable with her comments. And you refuse to let her do that to the grandkids when they are old enough to understand. And tell her it saddens you to hear it also. Tell her you understand that she worries about accidents and other issues but you all do your best to be safe and healthy. Good luck.