Betty,
Welcome to the forum.
I am so sorry you have to be a part of it.
And so sorry to hear about your niece. She is going through so much!
3 1/2 weeks in the hospital, I agree with you: something isn't right.
IMO, surgery should be a last resort or to save someone's life, once the colon is removed, there's no way to put it back.
At this point, she is probably severely undernourished, and she might be having some reaction to the IV steroids ( sounds like she might have some steroid induced diabetes as well?)
I would suggest you look into LDN, low dose naltrexone.
Do some research on LDN - low dose naltrexone, you can search this forum as they are several threads on this. I can tell you it works!
Here's the Penn State research done by Dr. Jill Smith with LDN and Crohns Patients.
www.ncbi.nlm.nih.gov/pubmed/21380937
www.healingwell.com/community/default.aspx?f=38&m=2204683#m2222188, https://www.healingwell.com/community/default.aspx?f=38&m=2129791&p=1
I know it's not a standard of treatment, but it is very effective.
Let me know how else I can help you. And I pray your niece starts to feel better and they get this disease and its treatment under control for her.