You have gotten some good suggestions -- please don't let anger at a very few less than friendly posts stop you from taking a serious look at the good suggestions!
Is the issue stains or tears on the clothes? If so - possibly the kids just really make a mess during the school day and I'm not sure why the teachers would not realize that.
If the issue is that they say there is odor: If they are asking specifically about whether you have access to washing machines and laundry soap, the issue might be not the kids but the clothes. Yes, you wash their clothes, but if you air-dry them by hanging them up, or if the clean clothes stay in a washer, damp, for a while before being in the dryer or being hung up, they can carry a musty smell that frankly people can get used to and not really detect, but which might jump out at someone not used to it. I am not saying the clothes are not getting washed! I'm pointing out that even clean clothes can pick up and hold onto a musty odor if they aren't dried immediately and in a dryer or if they are slightly damp and then folded and put away like that. I have noticed this myself - at times I might put on a shirt and once I pull it on I suddenly can detect a slight musty odor that tells me the shirt didn't get completely dry at first and now it's dry but has that smell. It's not a body odor type of smell or a stink, it's... well, it's more a damp laundry smell that dries into the fabric. If that's the case, you aren't doing anything wrong, you just might need to ensure that you move laundry immediately to the dryer and dry it really well so it doesn't have any dampness to it. Nothing to do with cleanliness or good hygiene or even good washing of clothes, just something that happens at times.
One thing to consider -- Bathing too often actually dries out the skin. It's possible your daughter's skin is dry (and dry skin does not always appear dry when you look at it, so it might not appear dry or flaky). When skin is overwashed and dries out, the oil glands try to compensate by producing more oil, and that might be happening during the day, and teachers might be noticing that.
And as others say, you could take your daughter to the doctor to see if there are any issues with medical conditions that could be giving her an odor that you, yourself, don't detect becuase you are so used to being around her. Diabetes can actually cause a person's body to smell; usually the odor is a sweet or fruity smelling odor but I've also heard it can be mistaken for body odor. If your daughter is thirsty a lot, drinks a lot, you should definitely have her checked for diabetes, as well as other conditions including urine leakage, excessive sweating etc. You may just not notice things because you bathe her so often that when you're with her, she usually has just gotten out of the bath or is about to have a bath.
Yes, it could also be that the teacher's just freaky but if this is possibly a sign of something medical, or an issue like the laundry thing, it's worth checking rather than getting mad at replies, right? I hope you get it figured out. I would approach the teacher with an attitude of "Help me figure out what you smell or see because I do not smell or see it, so let's work together on this."
The comment you mention about "being away from her parents" is a mystery to me and to others too - can you explain how that fits into the issue about the hygiene complaints?