You would include the distributions on your Oklahoma income. The retirement distributions are sourced to the state that you were a resident of when you received the distribution.
And yes, the Roth should not be taxable and probably has Codes 4 and B. There is an exception if the account was not open for five years prior to your mother's passing. The other IRA is taxable in its entirety unless there were any nondeductible contributions that your mother tracked, which is unusual.
