To do Alt + M C on Mac in Excel, download and install Accelerator Keys, then press Option, followed by M, C.
Command: Create From Selection
This is how to do Alt + M C on Mac in Excel with Accelerator Keys, the native ribbon and alt key shortcut solution for Mac users who get more done with Excel.
Alt + M C create From Selection creates named ranges based on row or column labels. Excel uses adjacent text labels to automatically name the corresponding data ranges.