Can someone please help and tell me what that little canister is
I can't exactly find what it is

 

I believe it's a one-way valve to prevent vacuum loss inside the booster. It stops the vacuum from bleeding out and back into the engine during low vacuum moments.

 

So I can't eliminate it?

 

It's A Filter.

 

Is the check valve incorporated in the elbow, then?

 

The check valve is the plastic piece the hose attaches to on the front of the brake booster. This is just a filter and was not used on all years and all models.

 

One more thing I have to ask is can the canister be hooked connected to the intake manifold or does it have to be on the carb

 

It can be connected to ANY full-time manifold vacuum source.
That filter is to help protect the large power brake vacuum diaphragm from gasoline fumes attacking it and shortening its life.
The one-way valve is in the elbow connector at the brake booster.