It is wonderful that you are so close to her, and that your friendship runs so deep that you want to be close to her even in this time of sadness. I wish we all had such friends :-)
That being said, I'm wondering if because her family has lived so far away and not seen her often... now that they've flown in and it is "the end", perhaps they really need this time to focus on their relationship with her in these last times? And can we blame them for being jealous of their time with her?
Also, there are 101 interruptions when patients are in the hospital. Nurses, doctors, respiratory therapists, nurses' aides, dietitians... Of course she needs a break to rest and some peace. I don't blame the family for limiting phone calls at all. If your cooking group hasn't yet, I'd suggest making a contact person who is the ONLY person who contacts your friend/friend's family on behalf of the group. Hopefully that person can express the group's love for your friend, and state that you all don't want to be a burden at this time - get a verbal okay for this contact person to call the family member once or twice a week for updates on your friend's condition (or whatever is confortable w/the family, assuming your friend is too weak/sick to do this herself). Certainly, send a card, and call the hospital unit she is on to ask about other restrictions (flowers, latex balloons, etc). But if the family has already refused other offers of help - I'd say just graciously accept their refusal.
Other ways to show you care - get a group up to do a cancer bike ride or 5K walk in her honor...take a donation and donate something to the cancer unit...something along these lines.
Good luck!