This is not a known method of transmission. It is highly unlikely that the dog scratched your friend to the point of drawing blood, that this blood remained undisturbed in the dogs paw for three days, and then the dog scratched you deeply enough to draw blood. Even in the case of a health care worker who should experience an accidental needle stick involving a patient with known hepatitis see the odds of transmission are only about 1.8%.
So no, the scenario you have described is exceedingly unlikely.
I am wondering why your friend hasn’t had her hep c treated. Today with the meds developed over the last few years hep c in now very curable for the majority of patients with cure rates as high as 98% and greater.