Hello Jayasuriya!!
The Diploma fee varies from college to college. If you want to study Civil Engineering in top universities or colleges then you need to pay more amount based on the college fee structure. The average fee for Diploma would be better 1 Lakh to 2.5 Lakhs. If your are eligible for scholarship then you might get fees reimbursement.
The hostel facility may or may not be their but that depends on the college. Most of the government colleges provide hostel facility. The hostel fee would be around 40 k to 60 k depending the luxury and facilities.
Hope this was informative :)
Thank you.