Ugh, that's always a pain.
The best way to handle this; (and it must be all done at the same time) is;
Change/ wash all the bedding (your kitty's).
Give the house and rugs a good vacuuming and sprinkle the rugs with flea powder in the area (you can vacuum the powder up after a few hours).
Give mama cat a light dusting of flea powder.
Take the kitten in the bathroom and with a fine toothed comb, brush out the fleas. Use a sink full of water to rinse the fleas off the comb (try not to get the kitten wet).
If this doesn't work, you'll have to seek professional help.
Oh, and as soon as your kitten is old enough (12 weeks), have it wormed. He WILL need it, fleas cause worms (in a round about way).
DON'T use any drops or baths. They'te to strong to have a kitten in contact with those.
Savas gave very good advice! If I could add something, though, you can also wipe the kittens down with Avon Skin So Soft, not the new one that is specifically made as an insect repellent, but the original one that is just made to soften skin. The original one still has bug repellent qualities, enough so that it will keep the fleas off the kittens until they are old enough to use an actual flea repellent on them. The kittens will be kind of greasy, but it's preferrable to the alternative of having them become anemic from blood loss to the fleas.