The timing of the apology may be of no consequence. Section 85 states:
"85 Vacation of office by failure to attend meetings.
(1) Subject to subsections (2) and (3) below, if a member of a local authority fails throughout a period of six consecutive months from the date of his last attendance to attend any meeting of the authority, he shall, unless the failure was due to some reason approved by the authority before the expiry of that period, cease to be a member of the authority."
What matters here is why the members were absent and whether the remaining members considered that to be an acceptable reason. All apologies must be accompanied by an explanation and that explanation must be debated by the council and either accepted or rejected. Crucially, as far as Section 85 is concerned, the debate must take place before the six months is up. So if your members didn't provide a valid reason for non-attendance, they're out anyway, reagrdless of any question about the timing of the apology or the status of the meeting.