“I’m down in the mill, Frank. I’m stuck in the gears and here comes the train with Mother Teresa and five hundred sinners on board, whoo whoo, whoo whoo. Who, Frank, who? who’s it going to be?”
This story makes it very clear that Frank has two main receivers of love in his life: his love for his sister and his love for religion. In this story, we see how both of them play two different but equally important roles in his life. He attends church regularly and repeats the sermons he finds particularly exciting, and he has a clearly strong and almost dependent relationship with his sister and how much she used to and does take care of him in life. When posed with the question above, Frank has to pause and take everything into consideration. Yes it is his sister, but she is just one person compared to five hundred and one, despite the fact that most of them are made out to be bad people.
Just like in the story he was telling to Frances, we never find out his answer. We’re never told whether or not Mike chose Benny or if Frank chose Frances. We can probably give a guess about either outcome, but we are never told for sure one way or another.