Of course I wouldn’t ignore it. But I wouldn’t publicly defame her if there were no physical/actual evidence to support the charges.
And what physical evidence is sufficient to make you suspicious of a person watching your child?
Ignoring an accusation because evidence is difficult to obtain is myopic. My experience has been that these accusations are accurate. If you watch “To Catch A Predator” a few times, you will realize that these people exist in vast numbers.