Database
[{"_id":NumberLong(1),"A":NumberLong(0),"B":{"arrayC":[{"X":NumberLong(128),"Y":"COMPLETED","Z":NumberLong(50)},{"X":NumberLong(109),"Y":"PENDING","Z":NumberLong(0)}]}},{"_id":NumberLong(2),"A":NumberLong(0),"B":{"arrayC":[{"X":NumberLong(128),"Y":"PENDING","Z":NumberLong(50)},{"X":NumberLong(109),"Y":"PENDING","Z":NumberLong(0)}]}}]
Query
db.collection.find({"B.arrayC":{$elemMatch:{X:128,Y:"PENDING"}}})