i think there are two options,
1 is to remove the floorboards and replace them
2 is to clean them as best as you can and then seal it with some sort of paint
i think tose are your only options, because the smell will allways be there ragrdless how many time you clean it with chemicals its now penetrated the wood
sorry couldnt be more help, for the big pay id go with option 1 and it will guarantee the result, option 2 will only temporary work i think
thanx jonny