Will you please suggest me best option after Diploma in Computer engineering at the age of 18 among Job or further studies????

In my opinion, you should go for higher studies as you are of just 18 years so its best to got for learning. Acquire as much knowledge as you can because ultimately knowledge matters.

List of available courses after Diploma in Computer engineering:

B.Tech
B.E.
B.Arch
B.A.
B.Sc-IT
BCA
BBA
BBM
CCNA
MCITP
CCIP
CCNP
AMIE

B.Tech collages

• Annamalai University, Annamalainagar
• Bengal Engineering & Science University, Shibpur, Howrah
• Coimbatore Institute of Technology, Coimbatore
• College of Engineering, Andhra University, Waltair, Vishakhapatnam
• College of Engineering, Anna University, Chennai
• College of Engineering, Pune
• College of Engineering, Thiruvananthpuram
• Delhi College of Engineering, Delhi
• Govt. College of Engineering, Coimbatore
• Harcourt Butler Technological Institute, Kanpur
• IIIT, Allahabad
• IIIT, Hyderabad
• IIIT, Kolkata
• IIT, Bombay
• IIT, Delhi
• IIT, Guwahati
• IIT, Kanpur
• IIT, Madras
• IIT, Roorkee
• Indian School of Mines, Dhanbad
• IT BHU, Varanasi
• Jabalpur Engineering College, Jabalpur
• Jadavpur University, Faculty of Engineering & Technology, Kolkata
• JNTU, Hyderabad
• JNTU, Kakinada
• Malviya National Institute of Technology, Jaipur
• MANIT, Bhopal
• Motilal Nehru National Institute of Technology, Allahabad
• Mumbai University Institute of Chemical Technology, Mumbai
• Netaji Subhas Institute of Technology, New Delhi
• NIT, Durgapur
• NIT, Hamirpur
• NIT, Jalandhar
• NIT, Jamshedpur
• NIT, Kozhikode
• NIT, Kurukshetra
• NIT, Patna
• NIT, Raipur
• NIT, Rourkela
• NIT, Silchar
• NIT, Surathkal
• NIT, Trichy
• NIT, Warangal
• Osmania University College of Engineering, Hyderabad
• Punjab Engineering College, Chandigarh
• SGS Institute of Technology & Science, Indore
• SVNIT, Surat
• University Visvesvaraya College of Engineering, Bangalore
• VNIT, Nagpur