All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad (saw) is His slave and Messenger.What you told your mother-in-law about it being allowed for her to go out during the day to her maternal aunt's home is correct because it is permissible for a woman in her waiting period to go out during the day for a need. Therefore, it is permissible for her to go to the house of her grandson or any other house if there is a need for that, provided that she abides by the Islamic etiquette.For more benefit, please refer to Fatwa 105002 and 87144.Allaah Knows best.
(Source: islam_web) Classified in Women and Family > Separation of Spouses