I don't believe you can legally cancel a bank draft. It is not a cheque under the legal defintion in the Bills of Exchange Act. Normally, if a draft was lost or missing, instead of placing a stop on it like you would with a cheque, the bank would issue a replacement but only if you signed an indemnity saying that you'd accept laibility if the original turned up.
If the draft is not crossed AC payee only, then she could endorse it over to herself and lodge it to her bank account. In the circumstances, the bank may decide to ignore the date issue (especially as legally, a cheque can never go out of date, 6 months is banking practice but is not prescribed in any law)