Put her in a cheap pillow case and make a tight not, rubberband around the knot just to make sure she cant get out.

Then, put her into a plastic tub or box, and keep her warm. Not too warm though, high 70's to 80's if possible. Warm up your car first if you live in cold weather.

Any refrigerated poop, feeding info, set up info would help the vet. I'd rather your "friend" go with you, because they will be able to answer the vet's questions since you seem to know nothing other than the snake is very sick.

I also hope you are expecting your friend to pay for this.