Night Mother's Gaze is craftable, Night Mother's Embrace is dropable.
Actually no.
Night Mother's Embrace - dropped medium set from Deshaan, always has robus jewelry, weapon and armor in any trait
http://elderscrollsonline.wiki.fextralife.com/Night+Mother's+Embrace+Set
Night Mother's Gaze - crafted 6 trait set
http://elderscrollsonline.wiki.fextralife.com/Night+Mother's+Gaze+Set
I don't know where it comes from, but I definitely have both medium and heavy night mothers embrace on my sneaky character.
I can't seem to upload a screen shot, but I am in game double checking now, and I have a heavy chest and the rest medium armor and robust jewellry. There is no indication it is a unique item.
With TO I whink the jewelry drops in robust but when this set dropped in Hew's Bane you could get arcane and healthy as well.
https://forums.elderscrollsonline.com/en/discussion/comment/3470643/#Comment_3470643Item Sets
Night Mother's Embrace: Fixed an issue where this item set was dropping in Heavy Armor and with the Healthy Jewelry trait. It now drops in Medium Armor and with the Robust Jewelry trait, as originally intended.
The issue with the heavy armor drops instead of medium has been reportedly fixed in patch 2.6.7, 3 weeks ago:https://forums.elderscrollsonline.com/en/discussion/comment/3470643/#Comment_3470643Item Sets
Night Mother's Embrace: Fixed an issue where this item set was dropping in Heavy Armor and with the Healthy Jewelry trait. It now drops in Medium Armor and with the Robust Jewelry trait, as originally intended.
Maybe the heavy armor and healthy jewelry had dropped before this patch and wasn't retroactively fixed.