One of the choices that may be available to you is to begin collecting a survivor pension. To be eligible for a pension you must either be the spouse of the member or an eligible beneficiary listed under Option D.
Additional Resources for Survivor Pension
Taking a Refund
Alternately, you may be able to take a refund of the member's annuity account. If you are eligible to select this option, you can either take a direct refund, subject to a 20% federal tax, or roll the account over to another eligible retirement account with no tax penalties at the time of the rollover.
For more information contact the Refunds and Rollovers department at 617-367-9333 x857.