What Should a domain Model return when using an interface?

I have got an MVC application in which the Domain Model (Data Model + Business Model) resides in a different class library. I am using an interface exposing some methods which must return data but not necessarily the entire representation of my domain objects.

My question is How should I return the data?
Should I create a kind of view models on the Business Model layer and then match them with my real view models on the main application (views-controllers-viewmodels)?
Should I return this data as dynamic objects?
Should I return the entire domain object event I need a couple of properties only?
What is the best approach to follow?

This is an example to give a better idea about the situation:

//Domain Class
public class User
{
   public string UserName { get; set; }
   public int UserId { get; set; }
   public string UserPassword{ get; set; }
   public string FirstName{ get; set; }  
   public virtual ICollection<ApplicationUserTeam> ApplicationUserTeams
    {
        get { return _applicationUserTeams; }
        set { _applicationUserTeams = value; }
    }     

}


public interface ITrackAttendance
{
  dynamic GetUsersCompany(int CompanyId);

}

 public class TrackAttendanceServices : ITrackAttendance
{
    //Method returning a Dynamic Object???
    public dynamic GetUsersCompany(int CompanyId)
    {

        using (var _ctx = new TrackAttendanceDb())
        {
            return _ctx.Users.Where(u => u.ApplicationUserTeams.FirstOrDefault().Team.CompanyId== CompanyId)                    
                .Select(u =>
                         new
                          {
                            UserName = u.UserName,
                            UserId = u.Id,
                            userState = false

                         }).ToList();


        }

    }

}