Tom was walking by the Ewell home. Mayella asked Tom to help her out (fix a door for her and then get a box for her). Tom, being the nice guy that he is, complies but notices that something is wrong: the door is perferctly fine and the other Ewell children are missing. Mayella explains that she saved enough money to treat the kids with ice cream. As Tom starts to reach up for the box, Mayella jumps on him and kisses him. Startled, Tom tries to leave.
Bob Ewell sees all of this and yells at Mayella. From this point, the reader has to guess what happens. Most likely, Bob begins to beat his daughter for the "sin" she committed. Chances are there was no doctor called to report and record Mayella's injuries (after all, it would have cost Bob five dollars that he didn't have).