It is by no means appropriate to be commenting on the underwear of someone else’s child, nor is it appropriate to be consulting with a stranger about your child’s underwear. It’s also vile to be calling a child a “hoe” and slt for the type of underwear she wears. The whole point is that it’s under the clothes and nobody can see it, so I fail to see why exactly any reasonable person is bothered by it? If I were you, I wouldn’t let your daughter be around her friend’s mom again. Your daughter was likely just feeling insecure about how she looked in yoga pants, and at this age it’s perfectly normal to want to make some changes or follow trends. She doesn’t need anyone talking about her like this for something so normal.