If she does not have income this year, and had no filing requirement, then the opportunity to take a tax deduction for medical expenses is lost.
She can not carry it forward to the next year.
She can deduct form any reportable taxable income, on schedule A any medical expenses to the extent they exceed 7.5% of her adjusted gross income.
Medical expenses can not be carried forward or backward.
And they are not a refundable tax credit so she had to have taxable income in order to take advantage of this.