She doesn't have a choice. There is a consultant committee which determines all aspects of the retirement plan, and "that's that".
When it was announced her employer's plan was switching from Fidelity to TIAA, we tried to prevent her funds from being switched. No go. Then, we tried to move her money back to Fidelity. Again, "no go"... thanks to "committee rules". Just recently, however, we've been able to switch a majority portion of her assets back to Fidelity via IRA rollover. TIAA will now be imposing their monthly fees only on "current contributions"... which are small compared to total account value.
A general word of advice. If you've got assets in an employer sponsored plan... and it's eligible to be moved out to an IRA rollover.... DO IT!! You'll have access to a MUCH greater environment of investment opportunities as well as incurring lower fees. (And hey... the fees "add up" over the years.)