So sorry to hear about your father. I wish him, and you, well while recovering from surgery.
To answer your question, yes, there are dogs trained to assist people confined to wheelchairs. I've seen them many times in TV; they are usually Labs or Goldens. If you do an Internet/Google search I'm sure you'll find the information. It will be such a comfort for your dad to have such a companion.
Hope you find the ideal house soon.