Are the wronged woman and her husband considered disobedient if they fail to attend the wedding feast invitation of her aggressor mahram, and does the ruling differ in the case of a condolence gathering?

If the feast is for a wedding, then responding to the invitation is obligatory for the invitee personally, not for a general invitation. However, if you are discomforted by seeing the inviter, then you are not obligated to attend, especially if there is someone present at the feast who causes discomfort to the invitee due to animosity or envy. Therefore, it is not obligatory for you both to attend this feast; rather, it is advisable not to attend to avoid reigniting the problem. As for offering condolences, it is not obligatory, nor is it legislated to gather for it. Rather, condolences are offered to the deceased's family at the graveyard or wherever they are found.