I recommend Leomund's Tiny Hut. It's a 3rd level ritual cast spell for bards and wizards that lasts 8 hours. It is described as:

>10-foot-radius immobile dome of force

and among other things, it's description include this:

> Creatures and objects within the dome when you cast this spell can move through it freely. All other creatures and objects are barred from passing through it. Spells and other magical effects can't extend through the dome or be cast through it.

In addition, from the DMG page 48, on the Border Ethereal: 

> A traveler on the Ethereal Plane is invisible and utterly silent to
> someone on the overlapped plane, and solid objects on the overlapped
> plane don't hamper the movement of a creature in the Border Ethereal
> The exceptions are certain magical effects (**including anything made of
> magical force**) and living beings.

As long as the hag isn't within the dome's area when the spell is cast, you should have no issue getting an uninterrupted long rest.