Do I need to upgrade both LR 5.7 and Camera Raw 8.7 to import files from Canon 7dMark2? or is LR 5.7 enough or is camera raw 8.7 enough
Lightroom is a complete stand alone program and does not require you to have any other Adobe product on your computer.
Adobe Camera Raw is a plugin for Photoshop CS and is not require by Lightroom nor is it used by Lightroom.
However if you are using both Lightroom 5 and Photoshop CS6 /Photoshop CC and wish them to 100% compatible then you will need to update the ACR Plugin in Photoshop.
Lightroom 5.7 will work fine with your Canon 7dMk2. (Its internal processing engine is the equivalent of ACR 8.7)
To wit LR 5.7 is an alternative to ACR 8.7 Plugin in Photoshop, you do not necessarily need both.