You're a very kind person to surprise her this way. I hope your kindness is rewarded with a lot of future hikes :-)
P&S cameras that take filters are rare, and many that do require an adapter of some sort. I suspect there are a few that take them directly, but I can't name one offhand. Possibly certain "superzooms" that use a standard lens cap?
Your money probably is better spent on a used DSLR. It would take filters directly and would provide complete camera control, something few P&Ss do. DSLRs plummet spectacularly in value after purchase and are pretty commonly available. Maybe look at Craig's List and ebay?