There was no Mrs. Calabash.
As I heard it, Jimmy Durante stopped at a wayside restaurant going by the name of Calabash's. The proprietors had a different name.
Mr. Durante was so appreciative of the great food and good service that he promised to remember the cook on his radio program.
He made good on his promise, but he didn't use the actual person's name. I think it worked better that way.
As I heard it, he referred to his late wife as “Mrs. Calabash.”
He said it with such reverence at the end of his show that I think it was heartfelt.