How can I study for a vocabulary quiz on "The Interlopers"?

I am not sure what you mean by "study," but I think it is certainly possible to get a good sense of what words might appear on a vocabulary quiz over this story. Whenever I make up a vocabulary quiz, taking words from a text my students are reading, I make a special effort to choose words that I know are likely to show up in future reading assignments, standardized tests, or in conversations that students might have in life. It is not too difficult to read this short story and guess which of the words your teacher might ask you about. I would be likely to ask about the meaning of the following words:
precipitous (second paragraph)
dispossessed (second paragraph)
acquiesced (second paragraph)
pinioned (fourth paragraph)
pious (fifth paragraph)
interlopers (tenth paragraph)
languor (seventeenth paragraph)
succour (twenty-first paragraph); American spelling is succor
halloo (twentieth paragraph)
pestilential (twenty-fifth paragraph)
I hope this helps!