it's a very general question - I won't provide a specific answer, but some guidelines depending on your scenario.
If by "all the scores" you mean the scores of the players in that session, the host should have all the relevant information. The ending screen with the scores is then just a special scene with no gameplay and very simple logic for limited interactions
If by "all the scores" you mean the scores of all the players including previous and other sessions as well, what you need is an online leaderboard. There are some good tutorials about this, but roughly you'll need a simple database hosted and a basic server and a connection between your game host and the shared leaderboard to look up the top scores
'hope that helps !