its very easy to hide you Instagram story from selected persons.
open your Instagram profile and click on top right option like this
now select option "Story Settings" like this
right now you didnt select any person.
click on top option to select any person like this
now select any person you want to hide your Instagram story like i select 3 persons like this
now you select 3 persons from whom you want to hide your Instagram story.
you can check it like this