Thank you for the question.
If you are going to create your footer with Visual Composer and display it in the same way on every page through the site you can follow this insctruction:
1. Create a new HTML Block with Visual Composer and add your elements there. (that you want to see in the footer)
2. Set footer layout to be 1 column in Theme Settings -> Footer.
3. Go to Appearance -> Widget and add “HTML Block” widget to your footer area with the block you just created.