I assume you are not using a drop down but using two checkbox fields? If so I would create three sections, put a single check box in two of the sections and a date picker in the 3rd section.
Then create a rule on the checkboxes. If the Active checkbox is checked then hide the section containing the Cancelled checkbox. You didn't specify but I assume the date picker field is only valid if the cancelled checkbox choice is used, if so then on the section containing the date picker use the formatting rule and the formula would be if the cancelled checkbox is blank then hide the section. You could also create a rule on the cancelled check box to hide the Active checkbox section if you like. Hope that makes sense!