All you would need is to add a Select-Object into the pipeline.
Get-ChildItem -rec -exclude *.exe,*.dll | select-string "[0-9]{3}[-| ][0-9]{2}[-| ][0-9]{4}" | select-object path, filename | out-file C:\1.txt
You could shorten the command line up with some aliases too..
<br> dir -rec -exclude *.exe,*.dll | select-string "[0-9]{3}[-| ][0-9]{2}[-| ][0-9]{4}" | select path, filename | out-file C:\1.txt <br> Good luck!