Translation:The child asks: "Where is mum?"
It rejected the child asks where is mom?
Apparently it's rejecting lack of a colon, quotation marks, or a capital W. I have never noticed it rejecting anything for punctuation or capitalization. I have just started using Duolingo a lot again after using it very little for a good while. Have they started caring more about punctuation or capitalization?
There's nothing anyone in this learner's forum can do about it.
Given the difference in text color, it looks like the outer quotation marks are automatically generated as part of the template and go around the to-be-translated prompt at the top of the page. If you ignore the outer quotes, the punctuation is correct.