feline making a mess upstairs on the floor

Question
13 yr old cat is not going in litter box, but she was just diagnosed with eggs in stool today and i was given 2 Drontal Feline pills.  will this cure her?and the litter boxx is downstairs and my vet said she may have colitis from the eggs so that is why she cant make it downstairs to the box. does this sound right to you? my father is going to put her to sleep if she makes a mess again.i have a week to make her better, so i am keeping her in my room with her food and water and a small box lined with puppy training pads and a few pellet litter on top.  what do you think

Answer
I"m not sure what you mean by eggs but I know that Drontal is used to treat worms in cats, which won't cure the colitis, switch your cat to a soft food diet and feed small amounts twice or three times daily and keep the litter box nearby your cat will need more veterinary care.