Is it possible to call the methods from contract A to Contract B without import statement?
An actual wallet is typically just an Ethereum address which contains the assets. And for which you possess the private key.
The trick in creating a useful wallet is to create a functional UI around the Ethereum address so you can interact with the assets (list them, transfer them, ...). Security is also an important aspect and due to security reasons it's typically discouraged to start writing your own wallet interface.
If you want to fork some open source wallet, you can for example have a look at https://github.com/MyEtherWallet/MyEtherWallet