Is it ok to have C or python program to process html form? Though I worked on php and java stuff.what are the disadvantages or advantage of such approach (using c/python)?
Its totally fine to write a CGI script in C to have your webserver process forms. Nothing stopping you.
However, for pros and cons, CGI/"web" languages tend to be built around the idea that they are a webapp. They come with functions for dealing with HTML, string manipulation, and database access. However, if you are more comfortable with C, by all means use it. Python is just fine too.