Pluma Dell was the daughter of Mary Frances Anderson and Henry E. Keatley, who were married 2 May 1878 in Brown Co., KS. Later, Mrs. Mary Frances Keatley remarried to Thomas Pitman Stanley. Then when her daughter Pluma Keatley died in 1895, the name Stanley was put on Pluma's gravestone. And somehow, a death date of Sep 25 was put on her gravestone, when August newspapers had reported her death being August 25. (see below)

All of the below, here in the bio section, is from Find A Grave member #48825891:

Mary and Pluma Dell were in the household of Moses W Drake in the 1880 census.
1880: Padonia, Brown, Kansas; Roll: T9_374; Family History Film: 1254374; Page: 382.1000; Enumeration District: 14; Image: 0186; dwelling 7, family 7, 1 Jun 1880:
Moses W. Drake, 59, widowed, farmer, b OH f b MS m b KY
Willis W, 8, son, b OH f b OH m b NC
Charles A., 6, son, b KS f b OH m b NC
Samuel H, 4, son, b KS f b OH m b NC
Elizabeth F, 9/12, dau, b KS f b OH m b NC
Oliver O. Stanley, 16, stepson, b IN f b NC m b NC
Ada V. Stanley, 14, stepdau, b IA f b NC m b NC
Mary Keatley [indexed as Hartley], 19, servant, keeping house, b MO f b IN m b KY
Pluma Dell [indexed as Plumsdell] Keatley, 1,b KS f b IL m b MO

The death was reported in the Brown County World (Hiawatha, Kansas)
Friday, September 6, 1895 - Page 5
Died at Horton, Aug 25, Miss Pluma Dell Keatley. Age 17

The Horton Headlight-Commercial, Horton, Kansas
Thursday, August 29, 1895, page 1
I desire to publicly express my thanks to all who have so kindly assisted during the last sickness of my grandchildren, Susan J Jester and Pluma D Keatley. The kindly assistance of Mrs E J Tucker, Mrs Liggett and Mrs Bowman merits especial mention. Their untiring efforts did much to alleviate the stricken ones and their afflicted friends. D B Anderson.

The Horton Headlight-Commercial, Hoton, Kansas
Thursday, August 29, 1895, page 8
At her home on West Florence Street,Horton, Kansas.
Miss Pluma Dell Keatley, after patiently enduring an illness of several days, passed peacefully away on Sunday morning at two o'clock Aug 25th, 1895, age 17 years.
She was a good girl and her memory is dear to all who knew her. Her remains were given their final resting place in the cemetery four miles north of Hiawatha.