If you’re looking for the French equivalent of You’re welcome being the answer to Thank you, it is De rien or Je vous en prie or Il n’y a pas de quoi.

If you’re looking for the French equivalent of You’re welcome being a salutation (as Welcome or Be welcome) then it is Soyez les bienvenus or Bienvenue.

When inviting your teacher to your place, you can start the conversation with

Bonjour. Soyez le/la bienvenu(e).

or

Bonjour et bienvenue.

or

Bonjour, je vous souhaite la bienvenue.

All fit perfectly the situation. You can also choose to add the name of your teacher after “bonjour”, or “bonsoir”.