any of them get it?
If you base the decision on the significance of the doll to each girl, then girl 3 should get it. If you think about it, if girls 1 and 2 don't go and get it, it won't directly affect them as much, as their desire for it was less; with girl 3, as she was the one who wanted it the most, it would appear, the outcome of the situation would directly affect her more.
Of course, there are many variables in this scenario, such as the ages of the girls. If girl 3 was youngest, then girl 1 or 2 should get it for her, as an act of looking out for her I feel. Or perhaps, more justifiable is that neither girl 1 or 2, in the given scenario, have suggested that they want the doll.