Separation of 11 years

well your mother an move for divoerce on the basis of desertion.. and you should mention the last adress of your father which was known to her.. and your mother cannot get a passport without mentioning your fathers name unless and untill she gets a divoerce.....

you have no information of whereabout for last 11yrs.this is ground of divorce if any spouse is missing for 7yrs.So your mother will get divorce easily .Give an an advertise in few news paper (national and local) asking him to contact you within stipulated time.Then approach court.

1. Get your mother an Advocate hired via reference
2. The only available ground for her assuming it was Hindu marriage is under S. 13 (1) (vii) HMA and certainly not under ‘desertion’.
3. The service to Respondent (husband) should be effected by substituted service.
4. Post decree in divorce u/s 13 91) (vii) HMA a Succession Certificate needs to be applied for all future purposes for heirs of father.
5. Post decree a certified copy should be applied.
6. Post decree she can get name Gazette announced if she does not want to carry divorced husband’s name.
7. Passport Form to be filled only post divorce decree. Under husband’s name it can be left empty whereas father’s name to be filled and thus your mother for Public documents purposes then on will be referred to via her father’s name. 

 7 years of not knowing whereabouts of the other spouse is considered natural death of marriage forms one of the bsais for dissoultion under HMA section, the above advise of tajobs is the best to follow.