Childs nasal flu vacine

Hi, I wonder if I can ask for some guidance.

My mum has just completed a course of FEC chemotherapy and I have now received a vacine consent form from my childs school.

I did ask mum to check with her oncologist if the spray was safe for him to have (and be around her) but she did not ask as she does not want her grandson to have the injection on her account.

She sees him regularly but I have read of the 2 week stay away after having the spray.

Is the spray a very real and probable risk to her and, if so, would he be offered the injection instead?

Thanks for any advice