The fee can be deductible as an itemized medical expense (in excess of 7.5% of adjusted gross income if your mother is 65 or older) as long as entry into the facility is on the direction or suggestion of a doctor for a specific (not general) ailment and the facility provides treatment for the ailment or condition. The fee does not have to be allocated in this case between medical services and other costs.
A business method of accounting requiring income to be reported when earned and expenses to be deducted when incurred. However, deductions generally may not be claimed until economic performance has occurred.