Who is Mr. and Mrs. Larsen from Shaking the Nickel Bush and what is their importance?

Mr. and Mrs. Larsen own a restaurant in Phoenix. They befriend Ralph and care for him while he is in the city. After Ralph buys a car, Mr. Larsen helps him and Lonnie repair the engine. The Larsens send Ralph and Lonnie off with a load of groceries and supplies to help them while they are on the road.