This may be spoilery.

Do you think that the MC should take the deworming medicine? It's pretty obvious that the tapeworm girl is gonna die, what from the nurse's reaction to the MC's request.

I think that the worm should go, as she is a mix between a parasite and steroids (with automatic roid rage).

Well first i think he won't take the Deworming Medicine, since that would be the end of the series. He should keep Sana imo, because the change in his behavior gets multiplied from not wanting to hang around with people etc. Most likely that will change over time at least thats how the plot can go...