It's just a matter of usage. You would be correct in calling Vasco, BCT, MAS and HYB a 'Terminus' as the tracks literally end in these stations.
With 'Terminal', it's a bit more vague. You can call Vasco, BCT, MAS and HYB as 'Terminals', because, in this context, 'Terminal' means the same as 'Terminus'. Howeverm you can use 'Terminal' as an adjective to describe a station. For example, Madgaon can be called as a 'Terminal' for Konkan railway, because a lot of train services begin and end here. In that sense, MAO is the end point for a service, so it can be called a 'Terminal' for that service.
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'Terminus' is a rigid word only referring to the final station on a line. 'Terminal' is not so rigid, and can slightly change it's meaning based on the context. So, if someone were asking a question, saying that a particular station is a 'Terminal' station, will be rather vague as it can mean that it is just a large, grand station where a lot of trains originate and terminate, or it can refer to a dead-end station too. And people tend to favor both explanations equally, so it can be confusing.