It is indeed taxable.

"due to her stepped up basis due to her father's death"

There is no Step Up in basis for this type of account or holding.

If he had basis in that account, she would inherit that basis status.

There are new rules concerning inherited IRA's, here is a link to start to research those rules. Also if it is a traditional IRA you need to find out if there is a basis, and if so, there are rules governing that distribution.    https://www.irs.gov/retirement-plans/plan-participant-employee/retirement-topics-beneficiary