It is very unfortunate that you have been terminated by your employer when you were attending your sick Mother.
You have mentioned that you were verbally terminated by your employer which is not clear. Normally many employers use to consider leave request from employees where medical reason is genuine. However when leaves are extended/prolonged without some fixed commitment of resuming back to work from employee side having no other option they may proceed with separation process as it hits the production count.
Still you can approach your employer by person with all medical documents and request for proper relief either by serving proper notice or payment in lieu of notice. Your employer might consider. At times communication gap will be the main reason for the conflict.
24th June 2019 From India, Madras