Database
[{"_id":"1","date":ISODate("2017-02-01T00:00:00Z")},{"_id":"2","date":ISODate("2017-02-01T00:00:00Z")},{"_id":"3","date":ISODate("2017-03-03T00:00:00Z")},{"_id":"4","date":ISODate("2017-02-02T00:00:00Z")},{"_id":"5","date":ISODate("2017-03-01T00:00:00Z")},{"_id":"6","date":ISODate("2017-02-01T00:00:00Z")},{"_id":"7","date":ISODate("2017-01-02T00:00:00Z")},{"_id":"8","date":ISODate("2017-01-03T00:00:00Z")}]
Query
db.collection.aggregate([{$group:{_id:{"$dateFromParts":{"year":{$year:"$date"},"month":{$month:"$date"},"day":1}},data:{$push:"$$ROOT"}}},{$sort:{_id:-1}},{$skip:0},{$limit:1},{$unwind:"$data"},{$replaceWith:"$data"}])