Question

For how long has the narrator's husband john rented the resort house for her rest cure

Answer 1

The story "THE YELLOW WALLPAPER", John, the husband, rented a house for the "rest cure" of the narrator.

They began their stay in the first week of summer. They celebrated 4th of July there. There was no specific date mentioned of when the rent will end. They were still staying at the rented house when the narrator finally became insane.