You cannot convert image (such as .tiff) to Excel spreadsheet (.xlsx). However you can simply import and paste image to the spreadsheet as object in any program capable of working with Excel documents.
Any utilities claiming that they can convert tiff to xlsx are basically creating empty spreadsheet with the .tiff image pasted to the first list in the document.
Unfortunately, there is no detailed software record in the database that match this conversion.
TIFF
Files with tiff extension are bitmap images in the Tagged Image File Format. Usually having the extension TIF, it's one of the more common graphics file types.
XLSX
Files with xlsx extension are s used by Microsoft Excel for its workbooks (spreadsheets) in Office Open XML format. XLSX is the latest spreadsheet format used by Excel with the adoption of XML formatting first used in Office 2007. While older xls files were in proprietary binary file format, xlsx spreadsheets use a somewhat altered XML scheme.