According to what I understand from the article, which is not written very clearly, she received a deposit of $50,000. She then withdrew $8000 and $5000 in cash. When she attempted to withdraw another $5000 in cash, the bank began to wonder why anyone in today's electronic age would need $18,000 in cash bills.
They questioned her about it and she was evasive and apparently combative, at which time they closed the account until they could verify what was going on with the account.
The author then goes on to say that even with, apparently, $13,000 in cash in her possession, she is unable to pay her rent, electricity, or to buy food.
This reads to me like a person who fell into some amount of money, and does not have even the smallest or vaguest idea what to do with it, therefore, they want it all in cash bills (under the mattress) until they can figure out what to do.
I did not even know it was still possible to pay rent or electricity with 'cash'. Who uses cash anymore? Except mostly for things that are sub-rosa, or illegal, or both.