Strictly speaking, the cost of your visits (mileage and tolls) would not be deductible medical expenses, even if you "pitched-in" to help an overworked staff.
From the IRS Publication 502, Medical and Dental Expenses : "You can include in medical expenses amounts paid for transportation primarily for, and essential to, medical care"
Your assistance, however much appreciated, was voluntary and not essential to the medical care of your wife.
The only exception would be for deducting the "transportation expenses for regular visits to see a mentally ill dependent, if these visits are recommended as a part of treatment."
