It's tougher decision that what you see, IMHO.
I would want the decision on whether to do chemo and radiation myself. These are not guaranteed cures, often they prolong life with great suffering in ever shortening intervals.
My mother got off this train; and after watching her go through it, if I have the choice, I will likely get off sooner than she.
Court ordered medical treatment - particularly for cancer - is offensive on its surface. There are some obvious exceptions, but I'd be careful to limit these.
These folks also cite the same Bible verses the Apostolic Charismatic Church of the First Born cites to justify shamanism and use of peyote.
I never, ever trust these guys to do anything but let their kids die and then bury them in secret graves.
I'm sorry about your mother. Fortunately for this girl childhood Hodgkin's has an excellent prognosis with proper treatment, while it is terminal without treatment.
In Florida a few years ago, a boy in his early teens was taken into protective custody because he decided against further cancer treatment. He was dying and just wanted to go home. Eventually, the court agreed with him and let him go home to die.
At that age, the girl is old enough to make her own decisions. I had cancer at the age of 15 and knew what I wanted to do.