In Mary (part one of Bailey's Cafe) what is the theme?
Hmmm... my guess is you mean the long section called "The Jam" where there are many stories from people who have lived through much suffering and end up at Bailey's Cafe. It is a place of pain and remorse.
There is nothing in back of this cafe. Since the place sits right on the margin between the edge of the world and infinite possibility, he back door opens out to a void. It takes courage to turn the knob and heart to leave the steps.
(See links below for further information.) One of the characters revealing her story is Mary, but she is better known as Peaches.
The theme of Peaches'/Mary's section, in my opinion, would be both guilt and self-mutilation. Mary/Peaches was shown kindness as a child, but lives in despair as a result. However, she is absolutely gorgeous. Her beauty made her a kind of a goddess to her father. No one is quite sure why (but the relationship with the father is the clue) Mary/Peaches not only seeks promiscuous sex but desires praise in that regard from each man she encounters. Mary/Peaches is absolutely guilt-ridden about these feelings. She doesn't want to give in to her sexual impulses every time and with every man.
As a result of the guilt due to both her beauty and her sexual prowess, Mary/Peaches practices self-mutilation and, specifically, we see her cutting her own face in search of her own ugliness. It isn't long before Mary's/Peaches' father arrives and wants to see his daughter. She refuses to see him until she can sort out her guilt and her pain. Eve is the savior here who promises dad that Mary will make it back home someday.