laptop freezing and restarting after win10 update

Hi, you could start with
a. which update are we talking about and which Windows build?
b. does she use disk imaging? (And if not, why not - so often users are advised to use this here)
c. has she checked the disk?
d. does this happen
- in Safe Mode
- after a clean boot?
e. Is there any useful information in
- the event log
- Reliability History

Yo may need to provide details of how to do those, which may mean using tutorials in the Tutorial section, or (Google) search.

If we are talking about the major Windows update from Version 1803 to 1809, you can always revert back to the previous version.
Windows 10 how to revert to previous version - Microsoft Community
If you can't boot into Windows, hold down the Shift key, and restart, and it should offer you the Troubleshooting menu where you can get to the same screen in the link above,