You are required to file as a part year resident of both CA and DC. You will also file as a nonresident of Maryland. Because you are are DC resident, you are exempt from Maryland tax. You will file the MD nonresident return and all withholding will be refunded.
Dear XXXXX -
If you review CA Schedule 540NR CA, you will see that in column E, you will only be taxed on your CA income. I have provided links to the schedule and instructions below.