There may not have been a 'James Ross', or rather not one that she was ever married to at least.
I noticed the birth certificate for Elsie jnr includes the middle name, Hyland and that Elsie snr was the one who registered the birth, rather than "James". Consider perhaps, could Elsie have been unmarried but wanted to look 'respectable' but also, if this was the case, wanted her daughter to grow up with her believed father's name as well as the Hyland name?
Given the death certificate for Elspeth Hyland is indeed "Elsie Ross (nee Hyland)" , and given no other surname appears on the death index, I am assuming, and perhaps you can confirm, she is only named on the certificate as Hyland and her 'husband' is not mentioned? Are either of her parents named, or were those details not provided by the son-in-law? You say "Her son-in-law gave the information and it is not correct. ". Do you say that because it doesn't refer to her as Elsie/Elspeth Ross? Have you considered that it may be that he and his wife knew there had been no marriage/husband, if that was indeed the case? How is she titled in the death certificate?
Had the birth certificate not been specific about date and place of purported marriage, I would perhaps have considered if Elsie and James had an irregular marriage. In Scotland, this was called 'marriage by cohabitation with habit and repute' which could apply to couples who had lived together and were thought to be married. This was rare, but did happen at times.
Could this have been Elsie snr in 1930/1935/1940, indexed as Mrs Elsie Hyland in the valuation rolls?:
HYLAND
ELSIE
MRS
OCCUPIER
HOUSE 44 SHAMROCK STREET
GLASGOW
1930
VR010201460-