There is probably no way how ASHX files could be converted to HTML. However, both files are text files, so you can open and edit them using any text editor.
Convert ASP.NET web handler to HyperText Markup Language web page.
We found one software available in the database for this conversion.
Microsoft Windows software - convert ashx to html on Windows
An easy to use, multiplatform web browser developed by Apple
Convert from ashx file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.