In Monster Hunter: The Wild, it is more important to work together to play in a team. If your friends want to do tasks with you, you can join the ongoing task by going to the task counter (talk to Alma) and then selecting the lobby member task.
How to do quests with friends in Monster Hunter Wild
Your friends can join the ongoing quest by going to the task counter (talk to Alma) and selecting the lobby member task. The tasks you just created will appear in their list. They can join by selecting the task and then select the first option "Post and leave (Quick Start)" on the next screen.