Is it possible to say in the home, or we should always use at home?
I am not sure whether I can use in the home.
In my understanding both are correct. However, they express different things:
"at home" it more general and usual. E.g. "I'm at home."; "I left my bag at home.".
"in the home" means more of like inside the house. E.g. "I left my keys in the home" (and you are locked out now; at home however would mean that you went somewhere and forgot them at home); "Where have you been? We waited in the garden for like hours!" - "I was in the home all the time.".
I myself would almost always prefer "inside the house / flat" to "in the home".
Both prepositional phrases are correct. If someone calls you, & asks, "Where are you, right now," answer, "I'm at home." Some office furniture looks attractive in the home. at home is specific. You're either at home, or you're not. in the home is usually general. Of course, every rule has exceptions. A television interviewer might report, "We're in the home of [some celebrity]."