If there is an arbitration clause in the bond signed by you company can send you notice for arbitration, and or can file civil suite.
Since the company has supplied a letter at your address company must have terminated your services and must have filed the copy of termination order in your personnel file kept with them.
Company should have supplied you a reminder/notice/communication stating either to join duties within a specified date or your services shall be terminated. Company should have supplied you termination order.
The question arises while company could supply you the recent letter mentioned by you why the company failed to supply you the reminder/notice/communication and termination order?
At a later stage company can produce the copy from their file and claim same was dispatched from their end.
Did you inform company in writing about your unavoidable family problems at home and apply for leave in writing and did you reply to the mail of company vide which company refused to grant you the leave, and do you have acknowledgment of all communications supplied by you?
It shall be appropriate to show all the records to a competent and experienced service lawyer and brief your case in detail and submit a carefully drafted and structured rely to company‘s letter, covering all points and build record in your favor. You should mention that no bond which claims to have signed by you was ever provided by you although you have been clamoring in person to get certified copies of loads of all forms/documents etc. which company made you to sign.
You may demand to examine your personnel file, in writing. You should proceed under expert advice of your lawyer.
You have committed the same mistake which majority of the employees make and suffer later.
If you can you should apply your negotiation, persistence, persuasion, reasoning skills and obtain a waiver and this shall be the quickest and easiest solution.