There are a couple of issues with your code from what I can see.
on your controller you are labelling it
[HttpGet]
so to access the code you must do a "get" in your JS you are doing $.ajax with a "Post" I would look at doing a $.get() (you can see that Vincent's answer has "Get" not "Post" in the $.ajax)
Ultimately using your browser's dev tools is your answer, the Network tab will tell you of any errors you are receiving.
In JS console.log() is useful for logging out variables.
I probably would use a Class rather than an anonymous in your db select
.Select(c => new<pre> {Address = c.address, MobileNo = c.mobileNo })
so it would be
.Select(c => new AddressClass = <pre> {Address = c.address, MobileNo = c.mobileNo })
An area where you will get some optimisation is rather than
var query = db.TICK_Dealers.Where(c => c.fullName == fname).Select(c => new {Address = c.address, MobileNo = c.mobileNo }).FirstOrDefault();
you should do
var query = db.TICK_Dealers.FirstOrDefault(c => c.fullName == fname).Select(c => new {Address = c.address, MobileNo = c.mobileNo });
or you even
<pre> var query = db.TICK_Dealers.Find(c => c.fullName == fname).Select(c => new {Address = c.address, MobileNo = c.mobileNo });