;with x as (
select ea.*, em.parentid,
row_number() over(partition by parentid order by score desc) as rn
from ExericeAttempt ea
inner join ExerciseMeta em
on ea.ExerciseId = em.ExerciseId
)
select attemptId, ExerciseId, Score, studentId
from x
where rn = 1
Result:
ATTEMPTID EXERCISEID SCORE STUDENTID
1 10 18 10001
4 13 22 10001
Result in Fiddle.