My son’s sixth sense?

We came back from my wife’s parents’ home.
Recently, my son(3 years old) very frequently said “Let’s visit grandma and grandpa!”,
so my wife thought “he may has a bad premonition.”.

And my wife worried about her parents’ health.
But it was only her imagination. Her parents were fine.

嫁実家から帰ってきました。

最近、息子くん（３歳）が、不自然なほど頻繁に「おじいちゃん、おばあちゃんのとこ行くー！」と言ってたので、ウチの嫁が
「もしかしたら、近い将来に両親に何かが起こって、それをこの子が感じ取ってるんじゃ・・・・」
と、ちょっと不安になっていたみたいですが、特にそんな事なく元気でした。

校閲の内容

We come back from my wife’s parents’ home.

come back → came back

so my wife thought “my son may has a bad premonition.”.

my wife though のあと、ダブルコーテーションを使うなら、my son → he
may has → may have （ダブルコーテーションを使わないなら、might have）

Then so my wife worried about her parents health.

Then so → So then は使いますが、Then so の語順はどうだろ…前述部分に So があるので、And でもよいかと

her parents health → her parents’ health

But it was a imagination, her parents were fine.

→ But it was only/just her imagination. Her parents were fine.
imaginationは不可算名詞の「空想」や「思い込み」のほか、可算名詞の「想像力」という意味があるため、可算にせず（a をつけず、her を足す）、定型的に「ただの」「単なる」を追加すると伝わりやすくなります