Just want to know which of them is better and more profitable in nigeria, Replies Please.

If you are good at what you do, you will alway be profitable,

Since this is Programming section your title is a bit off

Mobile App Developer VS Web Developer VS Software Developer

Mobile app and Web apps are ALL software. I guess you mean Mobile Apps Dev vs Web Apps Dev vs PC Apps Dev.

I have arrange them in order of revenue & ease of design. PC apps are usally the MOST expensive.

Mobile apps are still evolving. They are light, easy to design and sell (thanks to many app stores around). Device compatibility is the issue (BB, BB10, Android, IOS, Windows). Average selling price is $1.

Web apps are the best. They run on ANY device with a browser & internet connection. (They have been there since Sir Tim Bernes Lee worked on HTTP protocol. They will be around till Jesus comes). Most web apps (including website (like facebook), portals etc) sell at an average of $50.

PC apps are difficult to market and can be VERY expensive (games like PC games and console games inclusive). They are mainly corporate apps. Average price is $200. Eg. Apps like MS Office sell for like $100 - $500.