Formal:
* "Ma maison est à votre disposition." This translates to "My house is at your disposal," which is a polite and formal way of saying your house is welcome to them.
Informal:
* "Chez moi, c'est chez toi." This translates to "At my place, it's your place," which is a more casual and friendly way of expressing the same sentiment.
* "Tu es chez toi ici." This translates to "You are at home here," which is another friendly and informal way of making someone feel welcome.
Other options:
* "Fais comme chez toi!" This translates to "Make yourself at home!" and is a common expression used to welcome someone.
* "Tu es le bienvenu(e) chez moi!" This translates to "You are welcome in my house!" and is a friendly and inviting way to express your hospitality.
The best way to say it depends on the context and your relationship with the person you are talking to.