E-way bill for job work

Yes,you are correct. For inter-state movement of goods in relation to job-work, there is mandatory requirement to generate e-waybill. However, in case of intra-state supplies in relation to jobwork e-way bill needs to be generated only when the consignment value exceeds the threshold limit of Rs 50,000/-.(or whatever limit the respective states have now prescribed like in west bengal it is Rs. 1,00,000/-)

I am saying from the point of view of West Bengal GST law---

2nd proviso to rule 138 of the WBGST, 2017 says-

"Provided also that where goods are sent by a principal located in one State or Union territory to a job worker located in any other State or Union territory, the e-way bill shall be generated either by the principal or the job worker, if registered, irrespective of the value of the consignment:"

From the above paragraph it is clear that E-way bill is mandatory irrespective of the value only if the below mentioned both the conditions are satisfied:-

1) Goods are sent by principal to job worker and

2) There is an inter-state movement of the goods.

Further as per clause d to sub rule 14 of rule 138 and Notification No. 13/2018–C.T./GST:- 

E-way bill is mandatory for intra-state movement only when the consignment value exceeds Rs. 1,00,000/-.

Conclusion- It can be concluded from the above that in your case(intra-state movement form principal to job worker as well as job-worker to principal) e-way bill is mandatory only when the consignment value is more than Rs. 1,00,000/-.