Civicrm:ping INI file not found
I was just dealing with this and found your question..

Since you used C:\, i'll assume you're in windows.

TLDR; Try checking your PHP environment variable for 'HOMEPATH' vs 'HOME' and editing the file I mention below.

The first thing I will say is that you can increase verbosity of errors in civix by using -v, -vv, or -vvv options for most verbose. It helped me a lot with this issue.

I will leave the important details of my environment here as well, for others who may find this question:

A working Drupal 7 + CiviCRM 4.7.17 locally installed (manually) with MAMP on a Windows 10 machine, configured to use PHP 5.6.28. MAMP is installed to C:/MAMP and the site root is C:/MAMP/htdocs/drupal/

Civix is installed to C:/Users/"Eli Lisseck"/ and I am seeing the same behavior as you that civicrm:ping throws and exception.

Running the more verbose command civix civicrm:ping -vvv led me to the file C:\Users\Eli Lisseck\civix\vendor\civicrm\cv\src\Config.php line 54.

Check if it is looking for your HOME environment variable correctly, versus what you have under environment variables when you run php -i. I found it was only looking for 'HOME' but what existed was 'HOMEPATH'... so I added at line 52:

elseif (getenv('HOMEPATH')) {
      $file = getenv('HOMEPATH') . '/.cv.json';
      return $file;
    }


Now I get civix civicrm:ping Ping successful

Hope this is helpful!