She’s only just beginning her pregnancy. She won’t have a clue how she’ll feel once the baby comes, certainly not even two weeks into parenthood.
Don’t make a big fuss over this. Don’t discuss it further. Chances are she will want her mum around earlier than 3 months. You mentioned her in laws, who are likely driving her current thought process of wanting space. Don’t dismiss her concerns or take it upon yourself to convince her of anything. She’s an adult and her good and bad decisions are hers to make. However this lands, extended family are not the most important individuals in this scenario. Don’t make yourself, the other grans, or anyone else the main characters here. Support her as she needs. Remember that ultimately, we are not talking about something that will hurt the baby. I would hate to wait 3 months before meeting my grandchild, but I’d hate falling out with my daughter worse. It’s not worth it. You’ll get a lot of silly ego-driven responses, but no one on here has to live with any potential fallout between you and your daughter. I would keep that fact in mind over the next few months.