Getting out of the house is a bit of hassle tbh. Why not offer to visit her at home so she doesn't have to worry about that?
Like all things, it goes in stages. If she had a c-section or tore badly during the birth, that is hugely going to affect how active she can be for the first few weeks/couple of months or so. Not all women bounce back from birth injuries within a few weeks...often the effects linger on for months or even years, which people forget.
Then there's the disrupted sleep. People simply do not function particularly well if they're being woken every 2-3 hours for an extended period of time. That should get better as time goes on but there are no guarantees. Many young children are poor sleeps right up until they go to school (and some continue to be even after that - just see MN boards about 'My 5 yo won't sleep' or 'My 8yo is up at 4am every day').
It can also be quite draining looking after a baby. It's quite physical - constant nappy changing, bathing, lots of bending over, carrying them, chasing them when they start to crawl! And that's difficult when you're recovering from birth. Then all babies cry and need comfort, and some cry for hours on end due to reflux/colic. It's difficult to be particularly good company when you've spent from 5pm to midnight the night before trying to settle a screaming baby... it traumatises you to some degree. And then there's the feeding marathons...hours and hours of a baby attached to your breast when you're exhausted and sore.
Then there's the logistics of getting out of the house and caring for a baby away from home. For example, if you have a fussy baby, even basic hygeine like washing and showering can be a challenge to fit it if you're on your own without someone to hold the baby. It can be a struggle if you're sleep-deprived and your baby is screaming at the top of their lungs...you stop functioning effectively. It takes time to establish breastfeeding as well and not all women feel comfortable breastfeeding in public. Yes, some babies are quiet and latch on neatly so there's barely anything showing, and you'd hardly notice they were there but not all babies are like this. Mine needed everything uncovered and would scream loudly if they couldn't latch effectively, drawing all eyes to my state of semi-nudity 😬.
Though it's true that with the second one, a lot of these problems melt away because needs must. In my case, that means ignoring the screaming, mixed feeding and occasionally leaving the house knowing a nappy change is needed because I absolutely have to pick up my older one on time. You do lower your standards by the second one ime.