What reasons do gramps and sals father give sal for going on the trip?

There are three reasons Gramps and Sal's Father give Sal for going on this trip. The answer is found in Chapter Two "The Chickabiddy Starts a Story, Sal List"

1. Gram and Gramps wanted to see Momma, who was resting peacefully in Lewiston, Idaho.

2. Gram and Gramps knew that I wanted to see Momma, but that I was afraid to.

3. Dad wanted to be alone with the red-headed Margaret Cadaver. He had already seen Momma, and he had not taken me.