I'm not sure what my wife's AGI is from last year because, at the time, her Dad filed the whole family's taxes. What info do i need to put on my form from last year?

[Opus 17]

Your wife should have a copy of her tax return for her own records because she can be audited any time in the next 6 years.  Why won't her father give her a copy?  She can also register for an IRS online account and get her info that way.

https://www.irs.gov/individuals/get-transcript

If you filed jointly last year, your AGI is the same as hers.  If she filed separately (maybe single?) then you need to get the AGI from her return, or you can't e-file.