With very few exceptions (which don't seem to be relevant here), anyone is free to photograph anything and anyone as long as the photographer is on their own property, on property where the owner has given permission for photography, or in a public place.
As long as the woman is in a location which complies with the foregoing, she's free to photograph children in the street, in their gardens, or even through the windows of their houses as long as the pictures aren't 'indecent' (which requires nudity and/or sexual overtones) and her actions don't constitute 'voyeurism' (which requires evidence that the photography is for sexual gratification).
Chris