You do know that you have to file an I-130 as well, right? With the I-130 & I-485 concurrent filing, you can file for a new EAD for no extra fee. It takes about 3 months to receive the new EAD card.
I am not a 100% sure if she is allowed to work in between the expiration date of the old EAD and receiving the new one, but I would venture to say that she is NOT allowed.
Somebody else I am sure will chime in and correct me if I am wrong. Good luck!
I highly recommend this guide:
http://www.visajourney.com/content/i130guide2