I have not been able to find Mary Ann's obituary, but I did find a long article on Elizabeth Donnelly, aged 80 yrs. who died around the end of November,1894 in her home and James Walker of 1508 Christian was her executor.
In the article it states she came from Ireland over 50 years ago, which would have her immigration to the US be in the early 1840's. She may have been a sister to Mary Ann or Andrew.
I would like to send you the article but your email address does not show. If you email me at firstname.lastname@example.org, I will send you the article and anything else I can find.