Responding in a polite and respectful manner is important in maintaining a good relationship with your neighbor. Here's a way you can address their concern without mentioning anything about them:
"Thank you for sharing your concern. I appreciate your interest in our children's well-being. As parents, we prioritize the safety and health of our children, and sometimes that may mean limiting their outdoor playtime. We do encourage outdoor activities, but we also ensure they have a balanced routine that includes indoor learning and play. Your care for our children means a lot to us, and we'll keep your thoughts in mind as we make decisions for their best interests."
By responding in this way, you acknowledge your neighbor's concern and show that you value their perspective while also expressing your parental responsibilities and decision-making process without bringing up any specifics about them. This response aims to maintain a positive and considerate interaction with your neighbor.