Final answer:
Sal learns that Mrs. Cadaver's husband died in a car accident while traveling on a business trip.
Step-by-step explanation:
In the book 'Walk Two Moons' by Sharon Creech, Sal learns that Mrs. Cadaver's husband died in a car accident. He was traveling on a business trip when the accident occurred. Mrs. Cadaver witnessed the accident and was unable to save him. This event has a significant impact on Mrs. Cadaver's life and her relationship with Sal.