No version of Adobe Reader can open any spreadsheet file format.
Adobe Reader can only open PDF files.
Perhaps you can clarify your specifics.
I've been using Adobe Reader for over two years to view files with the .XLS extension on my iPone, it is definitely supported and is still the case with Acrobat DC, the only change now is that the formatting of the cells are lost...
[topic moved to Reader/Acrobat DC for mobile forum]