Is it permissible to wear the niqab only in the street to avoid the gaze of men, while removing it in private places such as the mother's or mother-in-law's house to avoid causing confusion?

It is more befitting for a woman to cover her face in front of non-mahram men. This includes the husband's relatives who are not mahram. It is not permissible to be in seclusion with them or to mix with them in a way that could cause fitna (temptation). It is also not permissible to uncover what should not be uncovered in front of non-mahram men. It is better for men's gatherings to be separate from women's gatherings. If covering your face in front of your husband's relatives is difficult for you, this does not prevent you from covering it when leaving the house, as Allah Almighty says: "So fear Allah as much as you are able."