R.Are the underlined sentences correct?
A: My mother left me when I was 2 yrs old and she went to Oman.
B: How were you brought up then?
A: Do you want to take that ball with you?
B: No, I have a ball at home or I have my own ball at home?
No, when you write a sentence as an example, you must keep it separate in some way from whatever is not the sentence. You made this same error in your first post in which "( means in new school)" should not be in the sentence.
I think you're asking whether either or both of these two sentences are right:
B: "No, I have a ball at home", or "I have my own ball at home."
If so, then yes, they are both right.
( Does the article a [STRIKE]will[/STRIKE] come here or is it [STRIKE]is[/STRIKE] fine without the artice a ? )
You need the article.