The children are being generous. They basically put a lot of effort into getting a present for Helen. And look! At the very beginning of the excerpt we can see that they are “delighted”; they are happy to be giving this present to Hellen!
The nickelodeon was a type of indoor exhibition space that was dedicated to showing projected motion pictures. These can be considered the beginnings of cinemas. Nickelodeons were cheap (they charged a nickel) and were particularly popular in the early and mid 1900s. This was due to several advantages.
First of all, nickelodeons were very affordable, which made them appealing to a wide audience. This came at a time when the urban middle class was rising. Moreover, these theatres offered a continuous selection of short films, which meant that they provided leisure activities at almost any time. The owners relied on "film exchanges" to have access to a wide variety of new films. This meant that the same audiences would keep coming back, as the content provided was new. This was a great advantage to the patron.