Answer:
Dickens's
Explanation:
To show possesion we tipically add an apostrophe then a (s), showing possesion. This is also named the "possesive case, or genitive". Some exceptions could apply according to the following rules of the English Language. However since it is a single noun as we note the pattern of apostrophe and s continues. (It is a Singular Proper Noun)
See the image below:
