You should choose JNU for distance education. It offers better faculties and learning opportunities. The classes, examinations, and results are declared on time. Jaipur National University has all four required accreditation, i.e. UGC, AICTE, DEB, and AIU. In terms of academics, facilities, and proper accreditation,  JNU is certainly better than Mewar University. 

Both JNU (Jaipur National University) and Mewar University are good in their own ways but it is suggested that if you choose Distance Learning you can go with JNU. 

You should make sure that whenever you are pursuing any course in distance learning, the  University should be affiliated with DEB.

Mewar University does not have DEB affiliation so once you graduate your degree will not be valid. JNU on the other hand has all Government Approvals like UGC, DEB, AICTE and AIU.