My opinion is this: If you think your employer would give you notice, a few weeks, and some severance pay if they intended to lay you off - you owe it to them to give a couple weeks notice if you intend to leave. If they’re scumbag employers that lay people off with no notice, no severance - then fuck them. Walk away with no guilt whatsoever.
The last job I quit, I was so happy, I was literally skipping down the street.
I got married right after that and never worked again. No sense both of us getting stressed out. 
At the very least she can say she quit to concentrate on school.
Don’t e-mail anyone…quit and move on. Jobs are like relationships…you have to get thru some bad ones to appreciate the good ones.
It’s been 20 years but this still kills me: a friend of mine working for the same company gave his 2 week notice and was kicked to the curb immediately - we worked in a cash business and they were concerned about money disappearing. Okay, I get that, made sense. So when I quit a month later, I figured why bother with a notice? I just told them “Hey, I’m quitting, I won’t be here tomorrow.” Oh, the wailing and gnashing of teeth and going on about how could I do this, I was like family, how sharper than a serpent’s tooth… It was so weird.
I left the new job about a year later. Same deal - two friends had gotten fed up, and gave a months notice which was kindly accepted, and they left in the company’s good graces after a month of farewell celebration. When I gave my notice, it was “pack your shit and get out now, traitor!” And unlike the previous two guys, they called me a couple of weeks later asking me back, offering a raise. 
Personally, I skip the Permanent Record/burning bridges worries. I think it was relevant when there was more of an old boys’ network, but most fields nowadays are too anonymous and no one gives a damn.
She’s given a good number of valid reasons as to why she quit.
Now, if they ask if she gave notice…
My employer escorts people out the door the moment they give their notice (after giving them five minutes to box up their personal effects). Needless to say, I won’t be giving notice when I leave.
Don’t fool yourself that you leaving will have an impact on upper management. They’ll replace your warm body with another one. Sunrise, sunset.