Is there a way to show Cell Date last updated?

The only reliable way involves VBA. This approach is a bit flawed.

Delete the values in B.

=IF(B2="","",IF(C2="",NOW(),C2))

(for the moment, use NOW, not TODAY... for obvious reasons).

File/Options/Formulas/Enable iterative calculations.

add values to B. The date/timestamp appears.

Overtype one of the values in B. Nothing happens (the flaw).

DELETE one of the values in B and re-enter another. The datestamp reappears, with the correct time.

IMO, VBA is the easiest way -- especially when you are looking for "date/time last updated"

If you are going to succeed at a worksheet formula only approach to this, I expect you will start with this tutorial (https://chandoo.org/wp/timestamps-excel-formula-help/ ) which shows how to do a "date/time first entered" type of timestamp. The problem I have always had is that "date/time last updated" is much more difficult logic to capture in a nested IF() formula. By contrast, a VBA change event naturally traps the cell that was edited, so it is easy to determine which cell was edited, and you can then easily write a date stamp to the spreadsheet when certain cells are edited.

Look over Chandoo's tutorial and see if you can at least make that work comfortably. Then you can see if you can figure out the correct logic to include in a similar formula to get your timestamp to behave the way you want.