The only way to unlock your Safe if you've forgotten your password and security questions is to use your Huawei ID (if it was previously linked). In Files, select Forgot password > Verify Huawei ID.
If you've also forgotten your Huawei ID password, go to this link to reset it.
If you didn't link a Huawei ID, unfortunately, it will be impossible to unlock your Safe and recover your files. You'll need to factory reset your phone to be able to unlock it.