cannot use sklearn.naive_bayes MultinomialNB to predict from one attribute
If your problem is shaped as you stated, you might need to reconsider your Naive Bayes model. MultinomialNB does not seem to be appropriate for your case. You can rather use the Naive Bayes classifier that uses the gaussian distribution.

from sklearn.naive_bayes import GaussianNB
gnb = GaussianNB()
gnb.fit(X, y)
print(gnb.predict(X))
print(gnb.predict_proba(X))