What expenses are allowed to a son who has been caring for his Mom the last 16 months full time 24/7?

IRS will not allow you or them any deduction for meals or drug store items or entertainment or heating and electric and never did. Medical transportation and co-pays are deductible if you itemize deductions. The IRS allows you to deduct qualified medical expenses that exceed 10 percent of your adjusted gross income for the year. Your adjusted gross income is your taxable income minus any adjustments to income such as deductions, contributions to a traditional IRA and student loan interest. See the instructions for schedule A at irs.gov