What is my cat dying from?

[bsajbel]

My 14 year-old, formerly healthy, active cat is nothing but bones now, despite eating just about everything put in front of her. She is moving slowly and we realize that she is near death, but are wondering if she needs to be put down or if letting her go naturally would be best. She is extremely frail and her eyes have turned an unnatural yellow color. They are producing a lot of liquid--almost tear like--that is a dark yellow color and builds up on her eyes very rapidly before crusting in the corners. What is she suffering from? Her behavior has become much more affectionate and sweet, as she used to be an entirely outdoor, independent cat. She willingly came into the house several days ago, seemingly as if she knows the end is near, too.

[Aleda M Cheng, D.V.M., C.V.A]

There are several conditions that can cause what you describe.  Some of them may be treatable or partially treatable if is not too late.

The following is a list of likely causes:
Hyperthyroid
Kidney disease
Liver disease
Cancer of almost any organ.
Feline Leukemia or Feline Aids, or other terminal infectious disease

Is it possible for you to have her evaluated by a vet?  It may or may not be too late for her but it is worth a try.  The yellow you describe is jaundice and occurs after there is some liver damage, but there is still hope since she is still eating, especially if it is hyperthyroid disease.

[peekawho]

Have you taken her to a vet?  

If not, that is what you need to do as soon as possible.  Your own vet can diagnose what is wrong with her, offer treatment if it might be considered helpful, and assist you in making the final decision if there is nothing left to do.