It is my understanding that some types of inherited tax deferred retirement accounts can be rolled into the retirement account of the beneficiary recipient. I don't know the rules and details on this. But I would expect that if the deceased was of retirement age at the time of their passing, then the beneficiary recipient would not have that rollover option and would at a minimum, still be required at a minimum, to take the RMDs that were required of the deceased prior to their passing.
Now I don't know the accuracy of the above, as I've not yet had to deal with such a situation.
