You can make it possible for people to use your locked phone to call a close relative in case of an emergency. 

Here is how;

When your phone is locked, it normally shows, enter password, under it you will see emergency. Click on  emergency, then you will see emergency information. Click on the emergency information (2 times).You will see a pencil icon on your extreme right, click on it to edit.

Next; enter the contacts you want to save as emergency. You can put as many contacts as possible but  save numbers of active people who know you very well (Family/friend).

The contacts you saved can be called even when your phone is locked without entering your password.*

To call a number in an emergency, click on ‘Emergency Call button’ and the numbers saved there will come up. You can call these numbers without unlocking the phone