Hello Nishita,
You can do both CA and B.com as the university has special courses for CA,CS and CMA. The one and only way to get Degree Certificate is studying degree in distance education(open degree). IGNOU is the one the best and government approved open university which is offered various Degrees in distance education manner. IGNOU offered various courses for commerce related students especially for CA,CWA,CS students. Below given courses offered by IGNOU for CA,CWA,CS students.

• B Com with Major in Corporate Affairs and Administration (BCom (CA&A))
• BCom with Major in Financial and Cost Accounting (BCom(F&CA))
  HOPE THIS INFO IS HELPFUL!!