Taxes in multiple states

My daughter recently moved from AR to DC where she works for a federal agency (the Social Security Administration). I know that I have to do an AR state return. 

1. Do I need to do a DC return?

2. Even though she works for the SSA, the employer address on her W2 is Denver, CO. Do I need to do a CO state return?

3. She has minimal interest income in Oklahoma where she maintains a small savings account.  Oklahoma is her home state. Do I need to do an OK state return.