MongoDB Map Reduce C# - mapreduce

Question

I am currently doing a map-reduce with the c# driver in Mongo.
I have got it working where the JSON is as follows:
{ "_id" : CSUUID("ef53b163-699c-462f-9135-b81bad115635"), "value" : { "firstname" : "Joe", "lastname" : "Bloggs", "groupName" : "System Wide Access" } }
What I want to do is flatten this object so as I don't have an Id and Value field, I only want the actual properties that are in my read model class.
Here is my code as it is currently:
const string mapUserGroupMember = #"function ()
{
var output = {groupId:this.GroupId, firstname:this.Forename, lastname:this.Surname, groupName:null}
emit(this.GroupId, output);
}";
const string mapUserGroupName = #"function ()
{
var output = {groupId:this._id, firstname:null, lastname:null, groupName:this.Name}
emit(this._id, output);
}";
var reduceF = #"function(key, values) {
var results = {firstname:null, lastname:null , groupName:null};
values.forEach(function(v){
if(results.firstname ==null){
results.firstname = v.firstname
}
if(results.lastname ==null){
results.lastname = v.lastname
}
if(results.groupName ==null){
results.groupName = v.groupName
}
});
return results;
};";
var groupMemberCollection = database.GetCollection("UserGroupMemberReadModel");
var groupNameCollection = database.GetCollection("UserGroupNameReadModel");
var options = new MapReduceOptionsBuilder();
options.SetOutput(MapReduceOutput.Reduce("MergedData"));
var results = groupNameCollection.MapReduce(mapUserGroupName, reduceF, options);
results = groupMemberCollection.MapReduce(mapUserGroupMember, reduceF, options);
I want to be able to call var collection = database.GetCollection("MergedData").AsQueryable<ReadModel>();
Any help would be appreciated.