mother in law

Mj
I am a nurse and on medical surgical units this time of the year I am often taking care of flu patients and contagious bacterial pneumonia and stuff like that. There's a reason why they do not want young children on the adult Hosp units like these ones.  I have a 10-month-old son and my mother-in-law took him into the hospital on one of these units to visit one of their neighbors who knows of my son and just had surgery. He likes my son a lot because she watches my son sometimes while we work and it always lifts his spirits. I DO understand the kindness behind wanting to visit and wanting to make his day a little brighter. But I'm not ok with it. I brought this up with my husband because he made a comment about him going to the hospital to visit him with the baby and I was upset that she did not ask us first.  I'm not sure if he said this in an attempt to save face with his mom or help soothe the situation but he told me that his mom asked him about it and he said sure not thinking anything of it.  But she works as a medical secretary she knows the type of things going around and she knows I'm a nurse and the fact that she didn't ask me irritates me a little bit. When it comes to my son she doesn't ask me nearly anything she just goes to her son which I assume just makes her more comfortable?  I Love my husband but he has no clue and he would probably just say yes anyway to save face with his mother not thinking it would hurt anything. 
That is if she really did ask him first. Yesterday the baby was diagnosed with influenza B and he literally only stays with me, my parents or his parents for when I work three days a week and that's it. He could've gotten it from anywhere but him going into an infested hospital where he shouldn't be on those units just increases his risk of picking something up. 
I made a point to message her and kindly say from now on can we not take him in the hospital is on the adult units because I don't want to risk him getting sick with all of the stuff going around. Of course she did not message me back. God forbid she asks my permission for anything. This is my child and he is sick. My husband seems a little irritable seemingly worried that she is going to bitch about it now. It's not going to stop me from kindly speaking my mind when it comes to my child though and what I'm not OK with. Am I wrong here?