D&D 5E - [5E] Shadow Monk multiclass options - Warlock, Gloom Stalker, or neither?

I have a Variant Human Shadow Monk with the following stats: 10 18 14 8 16 13 and the Mobile Feat.

It has a couple of deficiencies, that I'd like to plan towards correcting in the future:
1) Lack of innate darkvision. For someone who specializes in skulking around in dark areas, this is a problem. I can cast Darkvision on myself for 2 Ki, but that's taking away from other Ki-driven abilities.
2) Low-ish damage. More attacks, but middling damage, compared to stouter melee fighters, sneak-attacking rogues, and spell slingers. This gap will only increase in the mid-levels.

I'd also like to add a bit of extra out of combat utility, if possible.

It seems I have three main options:

A) Multiclass into Warlock for 2 levels after Monk 6. (This seems to be the "default choice" for most Shadow Monks.)
+ Low-level patron bonus(es).
+ 2 cantrips.
+ Hex. Bonus damage on every hit and enemy disadvantage, but requires concentration.
+ Several additional 1st level spells known.
+ Spells refresh on a Short Rest.
+ Devil's Sight. Long range darkvision. Can even see in my magical darkness, although I won't be slinging that around very much, since it hampers the rest of the party too.
+ Additional invocation. I'm thinking at-will Alter Self for out of combat disguising and trickery. Or at-will Silent Image, which combined with my Shadow Monk at-will Minor Illusion can produce moving illusions with sound for out of combat utility.
- Tougher option to role-play into, as I'd need to find the in-story opportunity to make a pact with a patron.
- Only 13 Charisma, so no Eldritch Blast. I'd have to stick to utility spells and cantrips that don't rely on attacks or saves.
- Delays Monk progression for 2 levels.
- Doesn't come online until level 8.

B) Multiclass into Ranger - Gloom Stalker for 3 levels after Monk 6. (I'd prefer the Revised Ranger, but I haven't talked to the DM yet to see if that's an option.)
+ Favored Enemy and Fighting Style. I'm thinking Humanoids and Dueling.
+ Hunter's Mark, for Hex-like extra damage every hit, although without Hex's accompanying disadvantage.
+ Couple of additional 1st level spells known.
+ Initiative bonus.
+ One additional skill proficiency. (Ranger is one of the only multiclass options that grants this.)
+ Extra utility with tracking, terrain, awareness, etc.
+ Extra attack in 1st round of every combat, which will help offset the loss of the Bonus Action while casting Hunter's Mark at the beginning of each combat.
+ Darkvision, plus being invisible to enemies' darkvision for extra stealth shenanigans.
+ 16 Wisdom, so can potentially have attack/save spells known, although I'll almost always be reserving my limited spell slots for Hunter's Mark.
- No cantrips, and spells refresh on Long Rest, so only three spells total per day.
- Delays Monk progression for 3 levels.
- Doesn't come online until level 9.

C) Don't multiclass, and just take Magic Initiate (Warlock) at Monk 4 or Monk 8.
+ Hex.
+ 2 cantrips.
+ Doesn't detract from my Monk progression.
+ By level 8/9, would be up 2-3 Ki over one of the multiclass options, which effectively offsets the 2 point "Ki tax" for Darkvision at that point.
+ Available as early as level 4.
- Darkvision is still reliant on Ki, can be dispelled, and only lasts 8 hours.
- Only 1 Hex/day.
- No other additional abilities/spells.
- Only 13 Charisma, so no Eldritch Blast.
- Costs one Ability Score Increase.

What are your thoughts?

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