A. Nobody home
B. Nobody's home
What is the difference between A and B?
Are both of them mean 'no people stay at home'?
Why is it not 'Nobody is at home'
 Nobody is at home. <grammatical>
 Nobody's at home. <grammatical; contraction: is => 's>
 Nobody's home. <grammatical; omission: "at" is omitted>
 Is there nobody home? <grammatical; question>
nobody refers to people.
All the best.