The image you posted is not the same as that on the Government website, it looks as if you have taken it from Ancestry. The image Shaun posted is from the Government Probate website and you simply follow the instructions.
Sometimes you have to replace the year of death with the year of probate, that is the case in this instance.
Do as Shaun told you and put in only her name and in the year of death put in the following year 1957, scroll down and you will see the image. Click to open the image and then you will see where to order on the right side of the screen, make sure on the order from you put both her first and midd names. It all goes through with no problem.
