Great job, Farax! What you wrote was really natural and was perfect English. Since the question already talks about children, you don't need to say 'children' again in your reply. You do need to add a pronoun, in this case 'them,' to make the reply sound more natural.

What you wrote makes sense, but so that we know who they’re giving their love and attention to, you can add children. Also, this is a fragment, and it might be good to practice writing a complete sentence. To make it a sentence, you can say: The best thing that a parent can do for their children is to give their children their love and attention. I hope this helps!