My cat has tapeworms, hasn't eaten in 3 days and I have no money?

You can buy over the counter meds for worms.

Take the cat to a local shelter to be euthanized.

If you can't afford to care for a pet, then you shouldn't have a pet. You should never have gotten her in the first place. Now that she's sick, though, nobody is going to want to clean up the mess and expense due to your negligence. The shelters are full of clean, healthy cats that they can't give away, and many of those end up getting euthanized. Nobody is going to sign up to bring a near-dead cat into their home.

I'm going to take a wild guess, and say that your cat isn't spayed, and it hasn't gotten any of its shots either. With all the vet bills, that is a VERY expensive cat, and there's no guarantee that it will even recover if it gets treatment. After a lifetime of neglect, the least you can do for the cat is ensure that it passes without any further suffering.

Your cat needs to go to the vet.

If you can't take your cat to the vet, take it to a local shelter and surrender it. IF you can't afford vet care then you shouldn't have a pet.