What is expected varies from rescue to rescue. Most want to make sure the house is suitable for a dog and the needs of the individual dog that is being adopted. Some will do the home check before bringing the dog over, but others will take the dog and only leave the dog with you if you pass the check.
Since they are brining the dog and would least her with your if it goes well, you need to be prepared. Having food and water dishes, a bed, crate (if needed) and other basic supplies set up will help. You should ask what food she is used to eating and buy a small bag of that so you have some one hand, if you want to change it you can but it should be done gradually. You may find that you need other supplies or what you have doesn't work for her, so be prepared to exchange things and buy other items as needed.
You should do some cleaning of your house. It doesn't need to be spotless, but should look nice.