Based on your friend's condition that the thesis research is not backed up by a Time Machine or sent via the Internet, the one last solution she can try is to utilize professional data recovery software.
Data recovery software can scan the files that are no longer stored on your Mac, including the replaced, inaccessible, unsaved, and deleted files. Then, it tries its best effort to retrieve lost files on your Mac machine.
Here, we highly recommend the secure and easy-to-operate iBoysoft Data Recovery for Mac. This Apple-trusted Mac data recovery app can scan your entire Mac hard drive and detect overwritten files with reliable, secure, and advanced algorithms. Then, returning all the lost data it scanned for you.
More importantly, it is designed with a user-friendly UI and has an on-screen guide which anyone who knows nothing about technology can do.
Step 1: Free download, install, and launch iBoysoft Data Recovery for Mac on your Mac.
Step 2: Select your Mac hard drive and click "Search for Lost Data" to find the lost files.
Step 3: Preview the scanning results by type to find the replaced thesis research.
Step 4: Click "Recover" to get back your wanted files.
Moreover, please tell your friend that she'd better have a habit of backup since nobody can take the consequences of data loss!