If the designated recipients are within California all she has to do is insure that the persons can legally possess firearms. Anyone receiving handguns in California must have a Basic Handgun Safety Certificate (unless exempted) and must register them with the DOJ. These transfers do not have to be processed through a dealer if the recipients are your children or grandchildren. [PC 12078 (c)]
If any of the firearms are to be transferred to out of state residents, they must be legally allowed to possess the firearms. The firearms do not have to be shipped to an FFL in the other state and can be shipped directly to the beneficiary. [27CFR 478.30(a)] There may, however, be state laws that would affect the transfer.
The procedures should be detailed in your will. You do have a will, don't you?