Would and SSD or RAM be the better upgrade in this situation?
Your logic is sound. Just something to keep in mind is that while yes swap is much faster on a SSD, it is still much slower in respect to RAM and both should probably be upgraded. But yes she would see the most improvement by going to a SSD

Just as a side note 10.10.1 will try to pre-cache as many things as possible in RAM so apple uses 'memory pressure' to reflect the systems demand for RAM.