As the skis are going to be used in bounds and needs to work on packed snow I would not recommend a fully reverse camber ski. Fully reverse camber skis are the best thing ever in pow but are not fun on packed snow. A regular camber underfoot and reverse camber in tip and tail ski would be best. I'm guessing she's not planning on landing switch so a really asymmetric sidecut ski (narrow tail) would be much more suitable. I have fully reverse camber ski (Kuros) and regular underfoot/reverse camber in tip and tail skis (S7s) and I pretty much always take the S7s over the Kuros when skiing in a resort.
My sister (similar in size to your mom) has S7s in 176 and loves them. But, she skis a lot of backcountry so the extra floatation from the length is useful. If your mum is wanting a resort pow ski then the smaller Voodoo (I think ROXY have the same ski but with their branding and graphic) is probably a better bet. It will still have more than enough float but be easier to throw around on piste.