Hip Replacement--or not?

Suppose your mother falls and breaks her hip, and she's in her 90s.  She's frail and thin.

Suppose she has mild dementia and can't always make her own decisions.  In a painful crisis, she may not be lucid enough to choose.

The doctor rules out surgery to repair the hip with pins because of osteoporosis.  She gives you two options: 

1) Give your mother a hip replacement--a serious surgery that she may not survive.

2)  Just put her into a skilled nursing facility (SNF) and drug her to the point where she doesn't feel the pain of being turned over or moved.  The survival rate after a broken hip is about a year in any case.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3597289/

What do you do?  What do you do if you and your siblings are divided on this question?

Here's an article that gives you all some background for the decision.  Thank you to reporter Lisa Esposito and U.S. News & World Report (and to my friend Dana for finding the article).

http://health.usnews.com/health-news/patient-advice/articles/2015/04/08/getting-a-hip-replacement-in-your-90s

Dr. Alexander Miric, an orthopedic surgeon at Kaiser Permanente in Los Angeles, stresses the seriousness of option two:
"...the mortality of broken hip without surgery is extremely, extremely high.”

Another sentence in the piece jumped out at me, a point made by Dr. Sharat Kusuma, director of adult reconstruction at Grant Medical Center in Columbus, Ohio:
"...Alzheimer’s-type dementia would rule out a patient" [for hip replacement].  

Catch 22:  Dementia cannot be definitively identified as Alzheimer's Disease until autopsy shows the tangles of plaque in the brain.  They thought my mother had Lewy Body Dementia, but it turned out to be ALZ.

Note to self: do not break your hip in your 90s if you get there.