I am not sure I can be of much help but in my experience people do often use different names so I would not discount on this factor. Three of my direct female ancestors used different forenames intermittently in census/marriage/baptism records etc none of which seem to bore any relation to each other. I guess it was just relatively common practice to change your name if you preferred something else.
Anyway onto your problem. Have you looked for the birth record for Janet? This should confirm the correct name of her mother and you will then be able to see if the marriage record for George Hendry and Bridget Matthews is correct, his occupation is listed as cooper so it would seem to be a strong possibility.
I can see from 1881 census return that Janet was born in Greenock Scotland abt 1872, Scotland is also given in 1901 census. If you go onto Scotlands People website and look up Janet Hendry born between 1870 to 1874 you will see that there are 14 matches. I suggest you sign up and buy some credits you will then be able to see some more details on the matches and then if you pay a bit more you will be able to click on the one that looks most likely in order to confirm - its not in a certificate format but it will give you all the info that you would find on an English certificate.
With regard to 1911 census I did find the Hendrys:
Name: George Hendry
Age in 1911: 68
Estimated Birth Year: abt 1843
Relation to Head: Head
Birth Place: Greenock, Scotland
Civil parish: Liverpool
Street Address: 3 Neville St Liverpool
Marital Status: Married
Occupation: Cooper Formerly
Registration district: Liverpool
Registration District Number: 453
Sub-registration district: Scotland
ED, institution, or vessel: 13
Other Household Members:
Mary Hendry abt 1847 64
Percy Hendry Nephew abt 1900 11
Liverpool, Lancashire, England
So again Mary / Bridgets birthplace is different. I do not know if there was some sort of situation with Irish immigrants in Liverpool or generally during latter part of nineteenth century that would have caused them to lie but the fact that George's birthplace is always given as Scotland shouts deliberate mistake to me!
No luck with the Hansans in 1911. What do you know of their history after this point? When/where did they die? Where did their children get married? Perhaps this might give you an indication of where to look next.
Hope this helps