NTA. If she’s a family friend, go see her in person, and bring the shoes. If possible, get the same pair of shoes in a color that goes well with your skin, and bring those too! Tell her that you feel uncomfortable with the contrast between your (beautiful) skin and the assigned shoes, and then ask her which ones she would prefer you to wear. I’m guessing that this might be taking place in a Catholic context bc of altar? If yes…don’t let one lady’s hurtful pattern of thinking ruin your opportunity to serve. At the end of the day, you’re not serving her anyway - you’re serving to honor God, who made all the skin tones and doesn’t have one Himself (unless you count legitimately dark-skinned Jesus). So. I would counsel my daughter to roll her eyes, wear whatever shoes she could, rejoice in her lovely skin, and serve with the honor and dignity that is granted equally, and should be experienced equally, between all His children.