Use up the balance for fare cards and use those cards while looking for new work or commuting to a new job as it will probably take a while for any new employee benefits to activate.
P.S. After looking at your history: Note that NYC MTA vending machines may have limits on how frequently a commuter benefits card is used (daily/weekly) for adding value to a fare card, so I would advise doing it sooner than later.
When I separated from a prior employer and I had commuter benefits, the company used WageWorks for managing the benefit.
You have ninety (90) days from your termination date to use your card to access the funds remaining in your account. After 90 days, you forfeit any pre-tax funds left in your account when you leave your employer, although you are refunded any remaining post-tax funds at the end of the ninety (90) day period. If you think a change may be coming, the best thing to do is log into your WageWorks account and adjust your elections as soon as possible.
As I did have a balance, I transferred the balance onto local mass transit fare cards. While technically the balance should have only been used for commuting expenses, the system did allow the 'purchase'.
Addendum to Answer
While not necessarily useful to OP, perhaps for someone else.
1) If you've moved, check the provider of the commuter benefits to see if they service your local region. That balance can be applied to service for your new city's mass transit system.
2) Should you still have the original transit purchase receipts (unclear if credit card statements are adequate) you can try to manually request out-of-pocket reimbursement. WageWorks has an check box in their commuter parking claim form for public transportation. I vaguely recall that this was how the old process for reimbursement worked prior to transit cards. NOTE Upon further inspection the public transportation option is only for those systems not supported by their transit card.
Where does the money go?
Since the participant cannot place any more orders due to their departure from the company, commuter credits are forfeited to the employer.
From what I can tell, the IRS rules focus on the fact that pre-tax dollars can only be used for qualified expenses/travel options.
It is optional for an Employer to grant this benefit. The Employer usually contracts the task out to a company like WageWorks to make sure that the Employee can only use the funds on mass transit/qualified travel options.
Readjusting wage information to the IRS for a layoff/separation does seem like it should be the obligation of the Employer, but in the US there are 'use-it or lose-it' Health Spending Flexible Arrangements (FSA) benefits so not needing to do payroll adjustment for smaller values like commuter benefit may be a lesser issue for an optional benefit (i.e. no one has tried to contest this one with the IRS). For FSA rationale see: What is the rationale behind an FSA being “Use it or Lose it”?