mDatabase.child("users").orderByChild("email").equalTo(u.getEmail()).addListenerForSingleValueEvent(new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        for (DataSnapshot userSnapshot: dataSnapshot.getChildren()) {
            userSnapshot.getRef().child("playerData").child("playerMoney").setValue(Math.ceil(tap(playerMoney)));
        }
    }

    @Override
    public void onCancelled(DatabaseError databaseError) {
        throw databaseError.toException();
    }
}

mDatabase.child("users").child(u.getUID()).child("playerData/playerMoney").setValue(Math.ceil(tap(playerMoney)));