。
All her friends went home and she felt lonely.
Literal
Friends [subject-が] all home [toward-へ] returned-and she [topic-は] was-lonely.
The te-form 帰って links the cause (friends leaving) to the result (loneliness). さびしい (寂しい) is the standard word for loneliness. The shift from が (friends as subject) to は (she as topic) marks a natural pivot between the two clauses.