This depends on so many factors that there's no possible way I could answer it. Six years ago, dh and I moved into my mom's place, partly due to the fact that our landlord (who lived upstairs) was nuts...but largely because it was a way that we, with our limited income, could help my mom with her mortgage and other expenses while she was in a financial bad spot. About a year and a half later, we lived there on charity, as my maternity leave for dd1 had run out, and dh's legal residency hadn't been sorted out so that he could work. We took over the cooking and most of the shopping, and mom let us live there rent free. Give and take, yk? We started out helping her out, and she ended up helping us out. Prior to that, she'd also loaned me the money for a lawyer, when my ex turned up in jail and I needed to get him served quickly with divorce papers (he wasn only in jail for a couple of months, and had no fixed address, otherwise).
When my uncle died, I sat beside her at the funeral, and held her hand and passed her tissues, and let her cry talk about him. That's something I think anyone could/should do for a family member who is hurting. When I was in labour with Aaron, she came to the house to hold my hand and see how I was doing. When he died, she took me to the funeral home to arrange his cremation, and she took me to ds1's school (4 days after the stillbirth) to talk to his school counselor, so they knew what was going on. She helped us shop. Those are all things I'd expect a parent to do, and I'd certainly do them for any child of mine in a crisis.
It's not that I think this stuff is part of my "job" or part of my mother's "job". It's that parent/child is an attached relationship, imo. While the childrearing aspect eventually goes away, the attachment doesn't. And...I once went and picked up a friend who called me in tears in the wee small hours, because her boyfriend had been verbally and emotionally and borderline physically abusive that evening and left her at home alone in tears. She was my friend, which is/was also an attached relationship, if a less intense one. My bff drove here from Colorado late in my pregnancy with Aaron, because she knew I was overwhelmed and wanted to help. We have an attached relationship, too.
I want my kids to be as self-sufficient as they can be, but I can't imagine ever refusing to help to the best of my ability in a crisis, no matter what the nature of that crisis may be. But, you know....I'd help either of my parents to the best of my ability in a crisis, too. Why wouldn't I?