With diabetes, etc. the options may not be anything other than a stent implant. Unfortunately, individuals with diabetes do not respond to an alternative treatment with medication. Also, a diabetic often does not get a feed back from the system when there is a serious ischemic event, and the results can be life threatening.
Additionally, a weakened body may not do very well with medication and could provide side effects that would affect the quality of life. Can't the blood pressure be controlled?
Is her weakness due to the blockage? or something else?
If it's due to the blockage, then the angioplasty should give good relief. If they didn't think your Mother was up to the procedure, then I'm sure they wouldn't recommend it. You also have to remember that Angioplasty is not very invasive at all, whereas I would be concerned if bypass was being discussed.