Is medication or a heart catheter better for a 96 yr old with blockage who previously was independent?

Only your loved one's Cardiologist can answer this question. Here is an article on the subject of heart catheterization from the Mayo Clinic:

https://www.mayoclinic.org/tests-procedures/cardiac-catheterization/about/pac-20384695

Normally, general anesthesia is NOT used for such a procedure, only calming medication is used to achieve a twilight sleep type of state.

In any event, the woman has lung damage now which nothing is going to fix. And, at 96 years old, if this were my parent, I'd vote for hospice care and allow nature to take its course now. Some events are impossible for a person of that age to recoup from; this may be one of them, since she's not eating and weak, suffering lung damage as well.

Wishing you the best of luck with a difficult situation.

At 96 I am with others on here that a heart cath may actually do more damage than good, and since she's already so weak she may not even survive the procedure.
If it makes you feel better to try some medication, then do it, but know that it's probably more for you than for her, as I'm sure at 96 she is just tired and ready to leave this world for the next.
You may want to instead bring hospice on board so she can just be kept comfortable and pain free in her final time here on earth.

I'd say neither would likely improve or lengthen her life. She's 96, for heavens sake, and eventually the parts just wear out.

Focus on the quality of life, not the quantity, I say.

If it means a major operation, I may not do it. Going under is very hard on the elderly. It takes a while for the anesthesia to leave their bodies. I think I would try meds first but that is something you need to talk to her doctors about.

What kind of "blockage" is this?