Further information has recently come to light which seems to settle the spelling of Frances Mallery's middle name.
In a conveyance dated 1898 of property in Balmoral Road, Gillingham, built by her son, Reuben Newnham, there is a plan on which the properties are shown as part of "MEZALER TERRACE". The name also appears in the text of the conveyance.
A quick internet search suggests this name may have French origins as there is a place with this name near Quimper in Brittany. Alternative origins are the name MAHALA or MAZALA, both of which appear to have many variant forms.
Interestingly, these properties are opposite the house which Reuben built for himself and his large family in Balmoral Road so that every day, when he looked across the road, he would have been reminded of his mother.