I'd agree with Bronte that Maynooth should be a reliable rental market plus it's an advantage having licensees rather than tenants. I'd just add that she might get lucky with one of the banks. I believe they have a certain percentage of cases per year where they're allowed to use their judgement to make exceptions to the normal lending rules. Anecdotally, they tend to front-load those in the first half of the year so if she applies in January for mortgage approval she might have a better chance of getting it then. Maybe someone else can speak to that.
If 14k tax free is enough to cover the mortgage, or near enough, she'd probably end up much better off after a few years, as long as the floor doesn't fall out of the rental market. Even if it did drop 25%, hopefully her earnings will have improved in a few year's time such that she has more capacity to make up any shortfall. That's assuming she can get the mortgage and you're realistic on how long she'd want to be there and the risks involved.