from what you have written I would make an educated guess that this is someone who has had a severe head injury and will possibly die or may not recover full function.
This happened to a friend's spouse many years ago and was pretty horrific all round. With the benefit of hindsight, if I'm right or even close to the situation, I would say
there is absolutely nothing you can do from miles away if you aren't local.
this is overwhelming for the family and it will be about getting to the hospital and being there all day every day. if you were local you could offer practical help of sitting with children so you can't. you will not begin to understand what they are going through or having to cope with as it is so far away from most peoples experience. This means it is very difficult to empathise or say the right thing.
This differs from grief where a regular 'I'm thinking about you' type text can mean the world because they are in the absolute eye of the storm and dealing with it day by day. Sporadic texts (definitely not daily) that make clear no reply is needed is a good thing provided its not intrusive.
If this is life critical, you may want to find out whether visitors would be welcome. In some cases, if it is end of life, good friends may be invited to say goodbye as it were but if that is you, you would expect to be invited. I warn you this can be very distressing to see. Short term if they are in a coma, some people welcome friends to sit and chat to the person as there is some theory that they may still be able to hear. Again you will be told if this is welcome.
If it's not life critical, you need to wait until the prognosis is known and settles which will be months, years even. THEN the surviving spouse will need masses of help navigating grief, self blame possibly depending on what happened, litigation possibly, managing the children through their grief at the earthquake that has just happened.
Do not start a go fund me as this could be hugely intrusive and distressing.
I am sorry your friend and her husband are going through this and wish them the best. It's likely their family will decamp to help because these situations are some of the worst things anyone can experience.