Seaborn, violin plot with one data per column

If understand your question correctly, you need to reshape your dataframe to have it in long format:

df = pd.melt(df, value_vars=['A', 'B'], id_vars='Success')
sns.violinplot(x='variable', y='value', hue='Success', data=df)
plt.show()

I was able to adapt an example of a violin plot over a DataFrame like so:

df = pd.DataFrame({"Success": 50 * ["Yes"] + 50 * ["No"], 
                   "A": np.random.randint(1, 7, 100), 
                   "B": np.random.randint(1, 7, 100)})
sns.violinplot(df.A, df.B, df.Success, inner="quartile", split=True)
sns.plt.show()

Clearly, it still needs some work: the A scale should be sized to fit a single half-violin, for example.