Hi, 

Some of the top government colleges for bca are 

Tamil Nadu:

• Government Arts & Science College for Women, Bargur

• Government Arts College for Men, Krishnagiri

• Government Arts College for Men, Ramanathapuram

• Government Arts College for Women, Ramanathapuram

• Government Arts College, Dharmapuri

• Government Arts College, Trichy

• A.A. Government Arts College for Men, Namakkal

• A.A. Government Arts College, Attur

• V.S. Sivalingam Govt. Arts College

Thiyagaraya Govt. Arts And Science College

Andhra Pradesh:

• Government City College, Nayapul

• Kakatiya Government Degree College

Jammu & Kashmir:

• Government Degree College for Women

Himachal Pradesh:

• Shaheed Captain Vikram Batra Government College

Hello,
I don't think that there is any top college for BCA but i can suggest you name of few top private colleges like BIT EXTENSIONS,AMITY UNIVERSITY,CHRIST UNIVERSITY, and many more...You can try for them and after that try for top NITs for MCA course.
Good luck.