How to label a dataset for making a classification model?

As a result of the possible responses to a questionnaire, I have 30 different variables and 60 observations.
From these variables' values, I have 5 subsets of data that each of them consists of some variables and some observations. Each subset has its own label which is a variable that defines the type of the observations and in one subset there is only one type as the label.
Now I want to make a classification model for new observations, should I combine all these subsets together into 1 dataset for building the model?
if yes, the problem is that the variables in all subsets are different and not the same and as a consequence of merging the subsets lots of missing values will be created, what is the solution then?
If not should I build 5 different classification models? and when I have only one label for all observations of a subset of data, how should I develop such a model?

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