i am going to suggest a few reading and research tips here>
https://familysearch.org/learn/wiki/en/India_Civil_Registration_-_Vital_Records2.
http://www.censusindia.gov.in/2011-Common/CRS.htmlhas the address of the Registrar of India on it .... you need to make a person to person agency contact for the enquiry you seek. As the period has registry of 98 percent of births deaths and marriages. fees will apply....
if your kin was a British Subject..... please look for her name on the findmypast index.... if she is listed then take the reference number and apply to the registrar of bdm of uk for birth cert....
older genealogical material may also include the use of the fibis site. type in India of the rootschat search engine and read some of the problematic things that happen with Indian records.
Guyana is not at overall , with a good coverage of microfilm work done.......
read the link for extended research>
https://familysearch.org/learn/wiki/en/Guyana_Genealogythere is not a great deal uploaded online for that country, and then one has religious issues so one needs to identify that and then approach the diocesan heads of that country or immigration departments or external affairs.... you dont state where you reside now and sometimes if you live in the commonwealth it is best to acquire the persons immigration files under freedom of information.... for example if you lived in Australia I would suggest the use of the National Archiv es of Australia site whereas your kins material would have a "P____" coded file that you can order...
try my suggestions firstly and come back on the post or contact me via personal messaging if the materials invoke the living...... good luck
fusion