The correct answer is: It helps the reader understand how precious friends and family are to slaves.
Indeed, slavery was a complex issue and several situations were possible for slaves. They would prefer not to escape and abandon dear friends and family. They would escape in order to later come and help friends and family escape. They would not have any friends or family but were too afraid to attempt escape. They would have no friends and family and thus would attempt escape.
The only constant value within these options is that they would always value friends and family if they had them.
