Yes, IF you are doing so for her benefit, such as to pay for her medical or living needs, or to pay off more expensive (e.g. credit card) debt of hers. The POA gives you authority but also imposes what is known as a "fiduciary duty," or obligation to act in her interest, loyally to her, and to not benefit yourself at her expense. Taking out a loan for your benefit on property where she owns 99% is NOT in her interest and would be a vioaltion of that fiduciary duty and could expose you to liability.