She cannot claim car insurance and repairs in addition to the mileage allowance.

This does not make sense. What is the mileage allowance? It seems commuting mileage is non deductible. The only mileage deductible is when there is multiple stops in one day. Will that small mileage deduction eliminate deducting repairs and insurance?

You cannot deduct all your insurance and repairs. You can only deduct the business percentage. For example, you drive your car 10,000 miles total in a year. The total of all those multiple business stops, during the year is 1000 miles. You may deduct 10% (1000/10,000) of your insurance, repairs, depreciation and gas, instead of the 53.5 cents/mile, if you choose. But, essentially, it's still based on the actual number of business miles driven. Commuting miles still do not count in the numerator but do in the denominator.