.. Getting light

Have you entered all rooms, already? ( Did you get into the study? )

There is a lantern in the study. Take the lantern.

You would need some matches. ( Go ask Mr. Jones where he was last night. He will give you matches. )

So, you have the lantern from the study and matches from Mr. Jones? Combine them in the inventory to create a lit lantern. Use it on the doorway.