INTENSELY annoying. YANBU @BarrelOfOtters I can only suggest as a few posters have said
'why don't you knock on my door and give me a lift?!' (Then again she might agree!! So only say this if you want it.)
'you'll cause an accident staring at my house whilst driving!'
or
'careful, you'll catch my husband hanging his red thong out of you're not careful!'
Sadly, I don't think any of the above ^ will stop her. Some people are just cheeky fuckers and think their opinion is soooo important, and that they MUST ask questions all the time. intruding and nosing into peoples lives. I can't imagine being like that.
Just recently I know a few people who have experienced similar...
.....One woman has been asked continually by one particular woman why she doesn't work, when is she going to get a job again, how can she not WORK?
.....One man I know has had a couple of colleagues at work wondering how he copes financially when he only works 3 days a week and his wife works 2?
...One young woman I know is grilled constantly by a cousin as to why she is not married yet, at nearly 30 and being with her man for 7 years?! 'why hasn't he asked you yet?' 
Also, re; the nosey woman in your scenario OP. One time a colleague of mine went past my house on the bus (when I lived on a bus route obvs) and took a photo of me hanging the washing in the car port as the bus was passing,' The bus stop was only 90 feet or so from my driveway, so the bus was only doing 10-mph when it passed... She put it on facebook and twitter 'for a laugh... #busyhousewifeinPeacockRoad and also tagged me in.
I was fucking steaming. Not only because she took the intrusive photo, but because it advertised to EVERYONE where I fucking lived. The house was obvious because it had a loft extension when no other house in the 30 houses in the road had one. I untagged myself on facebook, but couldn't on twitter, and I messaged her and told her to take it down. She called me uptight and said I need to chill. I blocked her on facebook AND twitter after that, especially when she refused to remove the posts with my photo on. I moved about a year later, and she left shortly before, thankfully.