Dear Rong,
Your Doctor friend can see you and your mother, he knows you, we are not in that position. So it is difficult to say anything.
However your mother does sound very ill, to fly long haul one has to have a fitness to fly. I think someone who has periods of unconciousness will not get this fitness to fly certificate.
Even if you went to the US for treatment it would not be curative. She would again need a fitness to fly certificate after any possible treatment to return home. Or of course you might decide to stay in the US if you were allowed the visa to stay till no more treatment was necessary.
I would talk again to your doctor friend who knows you and your family personally, it might be that your mother is very close to death indeed and then you would have to take into consideration all of wishes she might have had to be with her family at this time.
You are in a very hard position , but I would be surprised if your mother could fly, at all now. Although maybe in a private Lear jet at low altitude. The fits will be made worse in a plane at high altituded due to the lack of oxygen.
I am sorry my answer is not what you would want to hear.