I'm a bit surprised they told you that much, given that you're not the debtor on the account.
I'm not sure what to tell you, beyond the fact that if you catch up on what's owed the account should be current and thus there shouldn't be a repo. But it might make sense for your mom to let the repo occur, and then for you to help her find a cheap, older car to purchase and drive until she's able to afford car payments.
With a bankruptcy and serious default on a car lease, it's not that she won't take a hit on her credit score from a repo; but her credit's already in the toilet.

