Things got 'bad' 153 years ago according to the dwarven lore, though the actual problem began roughly 200 years prior to the current time. It began small, but the whole thing worked like a plague. It affected small pockets of population, spreading slowly, but exponentially. In this time it completely decimated the fey population; driving gnomes, halflings, and other 'lesser fey' into extinction. The elves suffered terribly because their birth rate is so low and so slow. They do not deal well with massive population decline. They also are not affected by the gems effects, so the other races resent them to some degree, mostly because elves will never have to kill their zombified loved ones, while most other races have first hand experience.
Human character will roughly be the end of the third or start of the fourth generation. Dwarves will be the second or possibly third generation when entering this scenario. Elves, if played as elders, will remember ALL of this. Even young elves will remember dealing with most of the problems when things got really, really bad.
Like I said earlier, things spread like a plague. It didn't collapse all at once, but when things started getting bad, people panicked. Strongholds and fortified cities became the only refuge. Humans and elves were fighting a losing battle and it was the dwarves and their engineers who saved humanity. Their technological skill allowed them to quickly and efficiently fortify cities and towns, carving vast havens directly from the mountain-face in some situations. The most prominent of these cities is the fortress of Haven. It's citadel is hewn from the living rock, the rubble being used to create the outer walls protecting the town itself. Haven is going to remain a place of legend until your characters reach it since it's a place that most people only dream of reaching in their lifetime. As such, the PCs will OBVIOUSLY be traveling there!

Humanity for the most part think things are bad and getting worse. Faith in the gods is incredibly strong in those who choose religion, but faith in general is very black and white. Most people either believe that the gods are with them or against them. For that matter, most gods have been abandoned, some becoming jealous and vengeful against those who remain, though their own power has weakened due to the lack of followers.
Funerary rites have changed drastically, becoming almost entirely cremation. Bodies are given a wake of 24 hours (Except in the case of death by zombie, in which case the corpse is decapitated immediately). When it has been determined that they are indeed dead and staying dead, they are cleansed and dressed for the pyre, and two silver coins are placed over their eyes. (Granted these coins hold no monetary value at this time, but they are minted specifically by the clergy for use in funerary rites. They are traded as tokens of favor for goods and services, basically ensuring a safe funeral for those who receive them).
Speaking of money, there really isn't much to work with. Almost everything is run in trade and 'credit' within individual towns. If you are traveling from town to town you'd better use your credit to purchase material goods since local 'Notes of Mark' could be quite useless in your next destination. Larger strongholds have been circulating Trade Tokens, though these are few and far between, and usually not accepted in smaller towns and villages.