There are plenty of posts out there on how to help (or at least not offend) families dealing with a medical crisis.
Can I give you some advice though? Sometimes, it seems people get hung up on their perception of what families need, instead of what they actually need. And if you're on the outside looking in (and that includes grandparents), you don't know the whole story, and it's never your story - it's about the child, not about you. It may be challenging for you as a friend or family member, but you'll never grasp the magnitude of how challenging it is for the parents, and the child's needs come before your wants or your comfort.
So let's talk about perceptions.
When you think about your friend or relative who now has a child with special needs, do you think, "oh, their house is always a wreck" or "that mom doesn't dress as nice as she used to or take care of herself the way she used to," or "they don't ever go out and they used to go out every week," or some other critique of how life has changed?
Sure, maybe they're depressed - it's very common in families with complicated kids. But, first and foremost, their priorities have changed. I know in our house, the bee-bee-beep beep beep of the pulse ox is going to come before anything else, even if it means burning dinner.
Don't assume you know what the problem is if you're not talking with them, asking how things are going, and being a part of their life.
Most parents in this situation find that of the many many people who say they will help when asked are never heard from again. Whether they don't know what to do, or are afraid, or embarrased....we never know, we just know that all our good friends no longer are interested in spending time with us. We get that our lives are complicated, that we have less time than we used to, that we often cancel unexpectedly....but that doesn't really seem like the sort of thing that should impact a friendship when we have a good reason for all of that.
Want to help them?
Don't ask what sort of book you should get them, or how to drag them to therapy.
Don't ask other parents what your loved one needs.
Don't think it's about you.
Here's the thing: If you want to help, do something, don't just stand there.
Wash the dishes, clean the toilets, or whatever else you see that needs to be done.
Ask about the medical things you need to learn to babysit. If they have other kids, take them to the park, or swimming, or whatever.
Interact with their child with special needs - sure, you may suck at it in the beginning, but they're still a child.
Bring dinner. Arrange to bring dinner to the hospital, or something that can go in the freezer at home for a day when time to cook goes poof. Call and say you're on your way and ask if you can pick up anything from the grocery store.
Are you seeing a trend here?