1. Tom went camping with his friend John's family.

Question

2. Tom went camping with John his friend's family.

3. Tom went camping with John's, his friend's family.

4. Tom went camping with John, his friend's family.

(Which one are grammatical?)

Answer 1

Only the first one comes close. Using the possessive form to try to express this type of thought will always result in ungrammatical or awkward sentences.

Try this instead:

Tom went camping with his friend John and family.