Group Multiple Tables in LINQ

this might help:

(
    from r in db.Rider
    join s in db.Spaces
        on r.SpaceID equals s.SpaceID
    group new { r,s } by new { r.SpaceID, s.SpaceCode }
    into grp
    select new
    {
        Count=grp.Count(),
        grp.Key.SpaceID,
        grp.Key.SpaceCode
    }
)

Where db is the database context

For grouping multiple tables you can do as:

group new { r,s } by new { r.SpaceID, s.SpaceCode }