This depends more on the profile that you make and the career you want to pursue or job you are aspiring for. If you are looking for a job in computer department I.e. It companies an stuff then MCA is a cool option otherwise you can opt. for the other option as well. It all depends on how you perform and what you want to pursue in future.

Hlw harshvardhan.

Hope you are doing well
After bsc maths, we can't say that which degree has a good job security either in msc or mca.
This thing is totally depend upon you that how much work you are doing to improve your skills or abilities.
Hope this helps.
Good luck

Dear Aspirant,

After doing B.sc maths you can do M.Sc in maths without any problem but if you will go for MCA then you have to struggle a lot as you don't have computer programming or anything related to computer science so if you are ready to go through the struggle and can score well in Masters then you can go for MCA else don't go for it.

Good luck