As a 6'2 woman who was always topping growth charts and taller than teachers in primary school, I speak with good authority here...
You will never be able to control these comments from strangers throughout dd's life, no matter how hard you try. And having a conversation with this parent, even if you think it would be beneficial for DD to overhead so she knows you're in her corner, I think is drawing attention to the fact that there is something wrong with her size and that it's rude to point out. Please don't let your DD shrink into herself or feel shame; I'm sharing the below with you from my life experiences in the hope it will help!
My mother used to say things such as "don't listen to them" and "sticks and stones" etc and when I brought up comments from people or strangers about my height, she would tell me to not be silly and that there was nothing "wrong with me". Whilst she did her best, on reflection as an adult, this was entirely unhelpful because each comment struck a nerve with me and I had no way of being able to talk about it and validate my feelings properly. It also led to eating issues as a teenager when "you're huge" began getting muddled in my head as "you're obese" and I also now have kyphotic curvature of my upper spine because I've spent a lifetime hunching over and trying to minimize my size and the space I consume because I've internalised comments about being "too big" or "too tall" or too "something" my whole life.
Even as a university student, semi attractive and outgoing, I would have comments from men who on the whole were possibly trying to flirt by emphasizing my height as a feature, and it just made me wholly uncomfortable and historically has never been something I've felt I could embrace.
I so wish I could have been taught strategies to handle situations with confidence and to feel beautiful in my body. I am getting there as a 30 year old, but 30 years have already been wasted feeling ashamed of something I can't change and undoubtedly led to health issues. Reframing, I find, can be helpful. I.e. someone points out your daughter is huge or tall, you could say things like "I know, isn't it wonderful? She's always been advanced in many areas for her age and I guess in height too, I'm hoping she'll take after me and we can share a wardrobe" etc. Or as she's growing and becoming a teenager "yes she's certainly tall! I guess she meets the textbook definition of beauty even just by her height alone!" But keeping open dialogue with your daughter too so she knows she can approach you about it. If you yourself have ever experienced comments like these, share them with your daughter in an age appropriate way. Normalise that people will do these things and just because many people will do this in her life, it doesn't mean there is anything wrong with this. It simply means it's a unique (highly coveted) trait. I think it's so important that children don't identify something about themselves and fixate on it as being a flaw, because it will stick and it will impact in later life too.
Ps, sorry that this mum said this. People suck! On the flip side, you never know, her children might not be flourishing in regard to height or weight and her comment came from a place of comparison and concern for her own kids - often people don't have a filter and it comes out wrong.
Hope this was useful! Happy to share a bank of witty comebacks that you daughter may find useful over the next 50 years 😂