technically, you're correct. the money lands in her bank account, so it become hers by default. however, from a moral perspective (i.e., a spiritual technicality), she knew the money had been deposited into her account in error and she knew who'd made that error (her bank). so while she didn't steal the money and technically it was hers after it was deposited into her account, morally she was beholden to give the money back to the bank, knowing it was theirs and that it had been deposited into her account in error. the hassles she's experienced since spending her ill-gotten gains -- including being outed on the internet, which will likely affect her job prospects from hereon in -- are a form of repayment. i'm guessing that she now wishes she had never received or spent that money. i hope she learned her lesson and i hope this serves as a cautionary tale to others.
Canada