enter link description hereIt would not seem that her iPphone/photos are connected to iCloud (specifically, iCloud Photo Library) If they were, Photos would not have let you imported them through traditional plug-in manner. This is due to the fact that the photos are not being really stored on her phone (besides possibly low-res versions) That being said, it does sound like the tick box for "delete items after import" somehow was selected.
My question(s) for you is: Did you not only delete the photos, but also go to the recently deleted folder and dump that as well? The PHOTOS app has a Recently Deleted section in the sidebar where recent deleted photos are stored temporarily for 30 days before they are automatically erased. If you have NOT done so, then the Photos will be in there and they can be recovered by selecting them and clicking the recover button Photos provides.
Option #2 : Does the Mac you are using have a Time Machine backup? If so, you would have an out where you can roll back the system or just the photos one day back before the decision to delete them and they can be recovered that way. I understand the time frame was pretty short of having those particular photos on your computer. You would need a backup that was completed in between putting those pictures on and deleting them. My desktop iMac is always connected to a drive, so it is making hourly backups. If it was a laptop Mac, I understand that chance would be much less likely to have made a backup during that time.