The home office would need to be her primary place of work. Driving from this office to an alternate place(s) of employment is dedcutible. Driving to/from work i(commuting) s not.
Note, when we have project employees, who may work out of a different client locaton for 6 months at a time, full time on a daily basis, they do not claim mileage deductions. If needed, we pay them a small upfront bonus to cover their additional costs because the new "primary office location" is the new project office. Project employees that drive from our home office, to site, once a week, do claim mileage.