Her children were:

Name:    Mother's Maiden Surname:
AVELEY, EMILY  MARY      WILLIS  
GRO Reference: 1892  J Quarter in HITCHIN  Volume 03A  Page 526  Occasional Copy: A
AVELEY, LILY       WILLIS  
GRO Reference: 1896  M Quarter in HITCHIN  Volume 03A  Page 553
AVELEY, MAY           WILLIS  
GRO Reference: 1894  J Quarter in HITCHIN  Volume 03A  Page 525
AVELEY, VIOLET  ROSE   WILLIS  
GRO Reference: 1899  J Quarter in HITCHIN  Volume 03A  Page 610
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Her death index:

First name(s) MARY A
Last name AVELEY
Gender Female
Birth year 1857
Age 70
Death quarter 1
Death year 1927
District Hitchin
County Hertfordshire
Volume 3A
Page 1157
Country England
Record set England & Wales Deaths 1837-2007

The birth date given here is very different to the 1862 consistently given in all the censuses of her married life.  The problem is that there were 4 Mary Ann Willises born in Berkshire between 1858 and 1862, though none in 1857.  This means it will be very difficult to identify which birth registration was hers, if any (as there was no penalty for not registering then).
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Their marriage index:

First name(s) FREDERICK ALBERT
Last name AVELEY
Marriage quarter 3
Marriage year 1890
MarriageFinder ™ FREDERICK ALBERT AVELEY married one of these people:
Mary Ann Willis, Elizabeth Taylor
District Hitchin
County Hertfordshire
Country England
Volume 3A
Page number 699
Record set England & Wales Marriages 1837-2005
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