Audrey should report the interest income from Form 1099-INT on her Form 1040 tax return. Specifically, interest income is typically reported on line 2b of the Form 1040 in the section for taxable interest. If she is using the simplified version, the information may be included in the appropriate section on that form as well.
It's important for her to ensure that the amount reported on her tax return matches the amount shown on the Form 1099-INT. If her only income is the interest from her Lending Bank account, then this will be the primary focus for her tax return regarding income.