As long as both of these were accounts owned by your mother (not inherited accounts maintained for your mother as beneficiary), the total RMD for both accounts can be satisfied by distributions from either account in any combination.
The penalty for failing to take a beneficiary RMD under the 10-year rule was waived for 2024 and prior years, so you don't have to take an RMD for 2024. If you don't, that just means that you'll need to take more in subsequent years. To avoid needing to take a large distribution in year 10, you might want to take more than your RMD each year.
