Janie does not get rabies, there is no evidence of that in the story. She returns home because she did not want to remain in the Everglades without him.
In the last chapter, "the flashback is completed, and the reader now sees why Janie is content to live and why she is the moral superior to the people of Eatonville."
My opinion is that, since the author made no reference to Janie getting the rabies treatment shots, that she, in fact, does contract rabies and chooses not to get treatment because she doesn't want to live without the love of her life, Tea Cake. Perhaps Hurston purposely left that part in ambiguity so the reader could write their own ending.