It sounds like you might be in a different account this year than she used last year. TurboTax can only transfer the AGI if you are in the same account as she filed in last year. Look back in her emails to see if you can find her email from TurboTax from when she filed last year (e.g. search for “welcome to TurboTax”) and see if you used a different username or follow the information here: https://ttlc.intuit.com/questions/1901486-how-many-turbotax-accounts-do-i-have

If you can't get access to her account from last year she can get her AGI by requesting a transcript here: https://www.irs.gov/individuals/get-transcript. You’ll need to request a “tax transcript” for the year “2015”.  Getting your transcript online requires you to have the following: your SSN, date of birth, filing status and mailing address from latest tax return, access to your email account, your personal account number from a credit card, mortgage, home equity loan, home equity line of credit or car loan, and a mobile phone with your name on the account. If you don’t have the following, you can also request one by mail, which has fewer of these requirements.

If you still can’t find her AGI you can always print and mail your tax return(s) instead of electronic filing, you don’t need to provide your AGI to print and mail.