Yes, Driders can be healed. However, they can't be changed back to their original form, or any other form other than that of a drider. There are no male or female driders; biologically, they're neuter, though they may appear male and female. Various entries say that the transformation can be undone with a <sarcasm>very common spell - Wish <sarcasm>.
4e's driders were actually a blessing from Lolth.
Faevras, right now, only has her innate abilities, plus those of a drider, to fall back on. Plus, she doesn't know English, has no magic besides her innate abilities, and has to deal with a problem that Dinah doesn't -- Faevras will need blood every four days, or she will die.
But yes, as has been speculated, Lolth has washed her hands of her, so has Eclavdra (who is the matron mother of house Eilservs). She was given some better clothes, and some money, and at some point, she'll show up on Dinah's doorstep. Panacea may have to get involved to keep Faevras from dying, or going out and killing someone and sucking their corpse dry so she can stay alive.
But that's for a future installment.