I have one query: is it valid to use "to" with "home"? Is this sentence is correct or not?
I am going to home.
In this sentence we are using "to" with the word "home".
Is it correct?
We generally don't use to in such context especially if you are going to your home.
I'm going home generally means I'm going to my home.
Note that if you are referring to someone else's home, the preposition is required.
I'm going to your home; I'm going to her home..and so on.
Note that the word home is a bit catchy and you may come across this word taking preposition.
"Home" is a noun as in "My home is my castle".
And "home" is an adverb in
I'm going home (where-to indication).
I'm at home. - Here I would see "at home" as a two-part adverb indicating where. But you find it only in older texts.
This is exactly parallel to German "das Heim (noun), "Ich gehe heim" (adverb, where to), "Ich bin daheim" (adverb, where).
In the meantime "at home" has been reduced to "home". When I learnt English about 60 years ago "I'm home" would have been considered a mistake. Language is always changing.