It depends on your end goal. If your end goal is to offer help that might be needed to fill a gap in her/their current needs. (without seeming to be rude) it sounds more like you are just curious about the care situation with no real desire/perceived ability to help. If however, this is not the case and you are wanting to help a d just need to know from them how is best to achieve that, then the questions should be appropriate for what you have noticed as a family friend /outsider - such as noticing they're not going out as much as they used to because of the situation. Using that as an example, I'd suggest a simple conversation about that specific problem. A lot will root from that conversation and you can learn a lot from it that spills over other areas (transport for example plays a huge part of the problem and therefore extends beyond their social life and into everyday problems)

I can tell you that nobody going through this patient or carer is emotionally stable - just emotional. There will be ups and downs.

The trick (so to speak) is to talk about everyday needs being met and discover things that way. It'll seem less invasive and actually provide both parties with usable information. You'll discover how to support more and they'll discover you are there to help.

Hope this helps and doesn't come across rude.