You wanna know why the hammer chose her? Because she's a fucking idiot.
No seriously, the Hammer decided it had enough of Thor and it wanted the dumbest human fucking being on the planet so it chose Jane Doh.
This woman had late stage cancer that was killing her, and the only way to treat it was to give her massive doses of rads that would most likely kill her. So then Thor takes her to asgard or she winds up there I forget which but I do remember what comes next. They say to her "ay yo, want Odin to cure your cancer?" and the dumb bitch says "no I'd like to die in pain and agony LIKE A REEEEL HOOMAN BEAN"
The gods literally offer her a free, no strings attached definitive cure for cancer, and she turns it down like a retard. Anyone who has cancer would take a free cure from god, ANYONE, but not this dipshit, bet it'd make great conversation at the cancer support group. I can think of two heroes who would've taken that cure right off the bat, Mar-vell and Deadpool, but it's too good for Jane jackass.
So she goes to earth, and proceeds to die of cancer, slowly, it's at this point that Nick Fury says something stupid and inconsequential that the hammer decides he's had enough and goes to find this idiot. I guess the hammer figures well, since Thor is gonna be a whiny bitch I might as well lend my power to this idiot and get her kiled while I'm at it.
Apparently, the hammer cures all diseases and maladies to those who weild it, except cancer somehow, but it flushes out the radiation for some reason, so she dies faster. The only way I could logically give this any credibility is that the hammer actively wants to kill this idiot for being such an idiot and to piss off Thor for being such a pussy.
God damn, I bet that hammer is missing ThunderStrike and Beta-Ray Bill, but no, it had to settle for Whore.