Cash for expenses should be included in an estate plan.
Some advice on how to plan for your family to access cash while your estate is being settled comes from South Africa by way of Personal Finance in "Will your family avoid a cash-flow crisis on your death?" The advice is applicable in the U.S.
Getting an estate through probate can take a lot of time, depending on the size of the estate and the probate laws in the state.
Your family will not receive the cash from your will for a while, in most circumstances.
If you do anticipate that your family will need cash after you pass away, the most effective way to provide it is normally to take out a life insurance policy. These policies pay out almost immediately upon learning of death.
Another idea is to open a joint bank account with a trusted family member and to put some money in the account that will only be used in the event of your passing.
Reference: Personal Finance (April 22, 2017) "Will your family avoid a cash-flow crisis on your death?"