The mother of the bride and mother of the groom dresses look best when they are within the color scheme of the wedding. If your colors are black and white, have the mothers wear either one or both of those colors. When you have both mothers (and other important family members) wearing the wedding colors, it signifies to others that they are your wedding VIP's. It also helps your photographer to spot the important people who need to be included in the majority of pictures. Including the colors of the wedding in the family's attire is key to pulling everything together.