DEAR MISS MANNERS: We were out to dinner with my husband’s college roommate and others. At the table, he loudly remarked to my husband, “Looks like you’re really losing your hair!” Everyone at the table was shocked by his insensitive and inappropriate comment. No one knew how to respond. He can be obnoxious and self-centered, and puts others down to elevate himself. Please advise: What should have been the comeback reply, even if it’s not funny? GENTLE READER: “Yes — and you, your manners.” *** DEAR MISS MANNERS: My mother’s 90th birthday is falling near her granddaughter’s wedding. She insis…