What you're referring to is called exclaustration. I'm assuming you're not a religious, but maybe considering it? If you do have aging parents who will need your direct assistance in the near future then you ought to divulge that to your superiors before admission. If you're wanting details for some project or just curious, the canons you're looking for are Can. 686 and 687
Can. 686 §1 With the consent of his or her council, the supreme Moderator can for a grave reason grant an indult of exclaustration to a perpetually professed member for a period not exceeding three years. In the case of a cleric, the indult requires the prior consent of the Ordinary of the place where the clerics must reside. To extend this indult, or to grant one for more than three years, is reserved to the Holy See or, in an institute of diocesan right, to the diocesan Bishop.
§2 Only the Apostolic See can grant an indult of exclaustration for cloistered nuns.
§3 At the request of the supreme Moderator acting with the consent of his or her council, exclaustration can be imposed by the Holy See on a member of an institute of pontifical right, or by a diocesan Bishop on a member of an institute of diocesan right. In either case a grave reason is required, and equity and charity are to be observed.
Can. 687 Members who are exclaustrated are considered as dispensed from those obligations which are incompatible with their new condition of life. They remain dependent on and under the care of their Superiors and, particularly in the case of a cleric, of the local Ordinary. They may wear the religious habit, unless the indult specifies otherwise, but they lack active and passive voice.
edit: sorry I didn't read all the way through your post. :o God bless you in your discernment!