DnD Head Canons

[Bohandas]

Night hags are an alternate form (a different caste, or just the female equivalent) of baernaloths.

I think you mean Yugoloths. "Baernaloth" refers specifically to Yugoloth archfiends (and specifically the most ancient Yugoloth archfiends, the ones who date to the time of the baatorans and obryiths)

EDIT:
Strike that. Apparently there's multiple canons and sometimes they're just an ancient caste of regular yugoloths