Neither one of those tire ratings is low enough to actually worry about her exceeding, so going by them it's pretty much a moot point.
One tire has an 80k mile warranty, the other a 75k mile warranty. Again, if she is only driving 2500 miles a year, the warranty is also a moot point.
There is no real reason to get the higher speed rating, which has a slightly lower warranty/expected lifespan. All else being equal though, the one with the longer warranty suggests a slightly harder rubber compound or some other reason why it would wear slightly slower than the other one.
I say it doesn't matter one single bit in this situation. Price is same, expected performance is the same, expected lifespan is almost the same. There really isn't anything to suggest one is better than the other for this situation, so go with either one.