This first episode was so dope...watched it a second time and I have two theories that I like for now.
One is simple...she had a rough night or disagreement w/ a BF (it was a Friday night and she was just trying to get away...anywhere but downtown which may have been where she left her BF). Found a dude she wanted to fukk to spite her BF / make herself feel better. BF comes to her spot to check things out, sees Naz passed out in the kitchen. Sees the knife on the table w/ blood and realizes his crazy chick played the knife game w/ dude...puts 1 and 1 together and sees a window for a perfect crime, and stabs the shyt out of her w/ the mark who will take the fall riding tequilia waves in the kitchen.
Second theory is a bit more out there but more

. Long read ahead so
Naz killed her.
-She's a fukked up, suicidal rich chick
-Naz is a simp
-She hops in Naz' cab w/ the intent of being driven somewhere to kill herself that night
-Naz tells her he's off duty, then folds and volunteers to drive her whatever
-This amuses her and plants the seed for what goes down that night
-She tests him again: "I'm thirsty" she says w / that testy bytch pout I'm sure some of you brehs are familiar with
-Naz complies again and pulls over to get her a drink, and you can see her get the slightest smile / smirk on her face
-shyt gets meta as the undertaker for the night (Naz) crosses paths with a literal undertaker
-Ole girl flips a cigarette carelessly at the professional undertaker pumping gas, and he has an issue with it as any non-simp with a backbone would
-Naz, undertaker for the night, asks "What's up with him?" (the undertaker)...she says "Who cares"...she doesn't give a shyt about the professional undertaker just like she doesn't give a shyt about her undertaker Naz
-She then asks Naz whose cab it is and he's shocked by the question..."Oh I don't miss much" she says...Naz is a mark at this point, she's got him read...the script is about to flip
-They talk and she realizes he's now passing up a party for her...she explicitly asks "So you're missing it...because of me." She's definitely got a mark.
-They stop by the river and he mentions how he usually does what everybody wants him to do, "ya know?" he says..."I don't, actually"

she says. She laughs...she has the perfect mark.
-Another test: "open your hand."... and she gives him a pill. He resists at first.
-Looking out across the river, she asks if he ever just wishes he could transport himself..."something bad happens here, and suddenly, you're over there"...foreshadowing breh's trip to Rikers...also a play on the notion from Greek mythology of a river dividing the land of the living and the dead, with an "undertaker" ferrying souls across
-She lays the sappy shyt on him about not wanting to be alone and it works. He takes the pill. She smiles.
-They get in the house...literally the first thing cut to is the deer's head hanging on the wall. Deer are associated w/ Artemis...the Greek goddess of hunting. In one myth, she turned an onlooker into a deer and had him torn to pieces by dogs.
"the only certainty is in what Aktaion suffered...and what Artemis did: the hunter became the hunted; he was transformed into a stag, and his raging hounds, struck with a 'wolf's frenzy', tore him apart as they would a stag."
What does Naz say as he puffs his inhaler? "It's fine now...it's cats...or dogs."
-You can also see a skull on the furniture immediately behind doe-eyed Naz as he stands in the doorway
-She pours more liquor and continues to feel Naz out...testing him with the knife trick on himself and then her..."Don't you do what everyone tells you to do?..."
-Then the coke comes out...they both take some and she drags him upstairs and they smash.
-Nas wakes up and he's in the kitchen, glass of water poured, fridge open, blacked out completely.
Now the pure conjecture:
-Naz didn't know but the coke was laced w/ scopolamine...a drug that makes you extremely submissive and prone to obey commands...borderline zombie status w/ amnesic effects
-Suicidal, stab-wound loving rich chick gave Naz one last command: stab me repeatedly...and he did. til she died. not realizing what he was doing in the moment and not remembering what he did after the fact
-suicidal chick gets her sadistic, manipulative deathwish, and now the hounds are coming for Naz