Adjustment of Status - I-485

hello dear friends! I'm new in this forum and I recently started the process to adjust status for my mother. I am a US citizen and I feel like I have collected most of the forms and pertinent information. The I94 is what we cant retrieve from the new CBP website. It finds my mom's information and previous trips in 2013. But it does not show any of her trips from Dec 2014 and her most recent trip in May 2015. We contacted the closest office to our city and they really didn't know what we were talking about. Finally an agent made a phone call and found my moms last entry and the I94 number. He said he couldn't print out any information and he wrote the number in some random piece of paper. I asked him why there is no any record online and he said it could take days to update and he wouldn't know why. Still today and we don't have an actual I94. I don't know what to do? Would USCIS accept her stamped passport and the number that officer gave us. Do we need to provide anything else to prove my moms legal entries to US? please advise.

thanks