In-laws or not, you'll be thankful you have them there to help with your daughter. Keeping her routine normal while your husband goes through surgery and recovery will make things infinitely easier for all of you. My twins were 10 when I had my surgery and keeping them "on task" with their daily routine was key to their emotional well-being; made them worry less about me.
Last words of wisdom. Tell your husband to rely on the faith and trust he has in his doctors. He has no control over this "situation", he should just try to remember that they have done this numerous times before and they will do their best. He shouldn't second-guess his treatment decision or his choice of doctors; he should find a level of confidence and stick with it. Recovery takes time - patience is key. Many days, especially the first ones, will be hard, but there is a light at the end of the tunnel - and it tends to get brighter as time goes on.
As a caregiver you will at times have a harder job than he does - especially tomorrow, when all he has to do is sleep
Take care of yourself, while you are taking care of him; let your in-laws take care of you when you need a break. Accept any and all offers of help - and don't be afraid to ask others outright for it. Most people you know will be more than happy to help you out - generally all you have to do is ask.
Tell your husband we are praying for him - and please update us on his progress when you can.
Best,
Jan