Stretch for an Air? (or 13" MBP)
One thing Apple does oh so well is to flatter the egos of the technologically ignorant with the way they design and approach their products. They also tend to address the wants of people who don't know what they're buying in terms of the average layman's default assumptions.
Durability wise, no Crapbook could be considered durable. But since e.g. blemishes are very visible, what happens in terms of the psychology of the typical user is that they automatically start using the Mac like a glass slipper - it's the single biggest thing I admire Apple for: the sheer amount of thought put into manipulating the user of the product into behaving as they want them to through the way the product is designed and in their choice of materials.
Lenovo, etc approach it from the other way around, that the machine is built for a degree of abuse because the the savvy user expects it. Apple subtly punishes you for abusing the product without the average user realising it.
And believe me, it works. It largely stops the technologically unaware (or just generally dumb) user from unintentionally abusing their machines, because the vector of abuse is in line with their normal expectations and assumptions. The less capable the user, the longer an Apple will last in their possession in comparison to whatever else they might have gotten.
And although in terms of core hardware reliability Apples are significantly lower than e.g. your similarly priced Thinkpad, the service you get out of a typical Apple Store is something that a typical mom can deal with, and moreover feel welcomed instead of alienated. Sign her up for One To One sessions on purchase and she might end up getting more out of the computer than you might have been able to get her to.
And designwise, a Thinkpad won't delight the mom. An Air will.