What if Mary and her mother are both colorblind is Mary's father colorblind too?

If Mary's mother is colorblind, and therefore carries the colorblind gene on one of her X chromosomes, then Mary would inherit that gene as well. If Mary's father is colorblind, he would have to pass on his X chromosome with the colorblind gene to Mary, making her colorblind too. If only Mary's mother is colorblind, Mary's father is likely not colorblind.