Is there a cat breed that produces a very small head and very large hips?

（My mother has a cat that is exactly that shape. Its colouring is black and white.）

Answer ：
No, all cat breeds are very well balanced looking animals. The only exception that one may consider is the Persian or Exotic where they have a small head due to the flatness of their face, but have a well built stocky body. The build of cat breeds aren't as extreme as many dog breeds, but I can't even think of a dog breed that has a small head and very large hips.
Your mother's cat sounds, ahhh, very unique. Her shape doesn't indicate she is in-bred, just that she's very different.