Answer:
B. Have you seen Lidia and Ben's hot new car?
Step-by-step explanation:
Possessive case is used to indicate possession. When we want to express that two or more animated objects own the same thing, then the possessive case is added to the last person in the list. As a consequence, only Ben -and not Lidia- receives the apostrophe and -s ('s) specifying possession.
The rest of the answer choices are incorrect because either the possessive case is applied to both people, or just the -s is added to one or two people.