Shiny:
Did your husband kept a copy of the paper works he signed in Canadian Consulate in Dhaka? Even though the visa processing centre is closed in Dhaka, the office is still open for other services. If your husband explained to the officer that he needs to fill out Form PPTC 028 and that form need to be sent to Canada where the mother has applied for his child's Passport, then the officer must send a confirmation to Canada.
See the following link: Even though it is for India / China, the requirement may be same for any country
http://www.canadainternational.gc.ca/india-inde/consular_services_consulaires/passport_under-passeport_moins_16.aspx?lang=eng&view=d
http://www.canadainternational.gc.ca/china-chine/consular_services_consulaires/passport-passeport.aspx?lang=eng&view=d
At this time, I would suggest that you change the date of your traveling to BD to sort everything out. No need to get stressed out. I know it is difficult for you but you have take it easy now.