Why would you make a library?
Libraries usually contain non-CodeIgniter specific functionality. A libary can be re-used by you or others in other projects. Examples: An authentication library and a mail library. It does not contain business logic. So some kind of 'Products Library' does not make sense.
Side note: If you make a library, it might be possible that it uses a MVC-pattern underwater, but the user of the library does not need to know this. The library needs to provide an interface/API and the end user definitely (YOU) does not access a model (directly). The interface consists of one class (sometimes more than one) exposing public methods to the outside world. The MVC-pattern.framework is most of the time not really suitable for a library.
As suggested, you can access multiple models from your home controller. It is perfectly fine to access the products model from your home controller.... BUT
you will find out that a lot of times you need some data coming from one model and combine it with data coming from another model. You have to perform some kind of business logic, but where do you put this?
It definitely does not belong in the view. (You only present/output data in a view).
It does not belong in the controller. A controller should be as lean/clean/thin as possible, so no business logic there.
So it should be in a model. That means you have to retrieve data form one model and pass it to the other... You cannot call one model from another one.
This is a situation you will find yourself in a lot of times. As far as I know, the MVC-pattern/framework does not provide a solution. Neither does CodeIgniter (or almost any other MVC-framework for that matter).
The solution would be to use a service layer (also called 'business layer'). The idea is that you access a 'service class' from the model, which gives the information you need. Example: In your case you could create a BlogService with a method "GetBlogs(DatetIme fromDate, DateTime endDate)". In the BlogService class you access all the models you need.
There you go!! Business Logic nicely separated from the controller (and the models), and that is a good practice.
I have to go now, but I will come back to this. In the meantime read something about service layers.
Anyhow, do not create a library.