If your girlfriend came to your house in the name of formally meeting with parents, if your parents have a good impression of this girl, they need to give her a red envelope. Because the woman is visiting the man's house for the first time, the man's parents should attach great importance to it and prepare good wine and food to warmly entertain her.
Of course, when leaving, if the parents have a good impression of the girl, they need to give her a red envelope as a gift and express the feelings of the groom's parents. The amount of red envelopes should be determined according to local customs.
But if your girlfriend is visiting your house as a friend, there is no need to give a red envelope because it is not a formal meeting with parents and may only be a chance to get to know each other. It is not yet time to discuss marriage, so only a simple hospitality is needed.
