How to merge columns, value count them and then plot the results?
It can be done like:

import pandas as pd
melted = pd.melt(df1, id_vars=["index"], var_name="Var", value_name="Score").dropna()
table=pd.crosstab(index=melted['index'], columns=melted['Score'])
%matplotlib inline
table.plot.bar() #for simple axes subplots