Final answer:
The best summary is that the family feels isolated and trapped by their unusual situation, indicating their emotional despair and perceived uniqueness of their misfortune.
Step-by-step explanation:
The paragraph summary indicating that the family feels isolated and trapped by their unusual situation is the best option. This captures the essence of the despair and grief the family is experiencing, largely due to their unique and desperate circumstances, contrasting with the idea of physically moving Gregor in a box which was logistically possible. The family is not simply impeded by Gregor's transformation or the logistics of moving him, but by the collective mental and emotional burden of their situation, which sets them apart from their community and feels inescapably unique to them.