In 2013, the AGI floor for someone under age 65 is 10% of AGI. The 7.5% floor applies to those 65 or older. Since it is you, and not your mom, who is taking the deduction, you must use the 10%-of-AGI floor.
A trust created during the lifetime of the person who created the trust. If irrevocable, income on the trust principal is generally shifted to the trust beneficiaries.