An excellent patron, the Hag has your patron bestowing their gifts upon you. The abilities are all hag related, which works well in terms of balance. The only concern I have is the 10th level ability: it dramatically empowers a caster (but we're talking Warlock, so that's mitigated a bit) by increasing the DC of their spells but it requires the Warlock to dwell in a location for days. I would personally have changed it to something like this:

"Whenever your warlock completes a long rest, an area around their resting site is empowered. This ability extends a number of miles equal to half your warlock level and lasts until you complete your next long rest."

And then give it the benefit. If you want to up the spell DC, increase it by half your proficiency modifier so it scales GENTLY with the character. (+1 up to level 8, +2 to level 16, +3 from level 17 up). This means the DC would be 8 + stat + proficiency + 1/2 proficiency, which I think is more reasonable than a flat +1 to +5 based on days. It becomes an ability that's more usable for the character but not as powerful (saving your monsters a little). Personally I'd rather just give them an additional spell slot as long as they're within that area but that's me.

Overall, nice work.