About a month ago I saw an article that the US government had recently uploaded all the images from the 1940s census. With a couple hours of searching I was able to find my grandmother who was only 4 at the time.
She is Frances. The one labeled “son” despite her having an “F” for female right next to it. The census taker must have been disgruntled. If you have the patience to go through sheets of the images it really isn’t that difficult to find people as long as you know where they lived. Simply go to http://www.stevemorse.org/census/unified.html and select the area you are interested in. Depending on how big the town is, multiple sets of images will come up. I was lucky Nana lived in a very small town so I only had to go through about 60 pages. If your grandmother lived in Brooklyn, sorry. You can click on the button at the top that says “ED Maps” and try to narrow down which sets of pictures you have to look through.