Is it Mongo.Collection or Meteor.Collection ?

The solution is,

    Meteor.Collection was renamed Mongo.Collection in 0.9.1. The change is currently backward compatible, however you should switch to using Mongo.Collection for any new projects. It looks like the docs have mostly been updated except for the wording in the Data and security section.

Alternate solution:

As per change in Meteor 0.9.1 you follow the link: https://github.com/meteor/meteor/blob/devel/History.md#backwards-compatible-renames

Backwards compatible renames:

Symbol renames:

1. Meteor.Collection -> Mongo.Collection
2. Meteor.Collection.Cursor -> Mongo.Cursor
3. Meteor.Collection.ObjectID -> Mongo.ObjectID
4. Deps -> Tracker