My mother-in-law left her husband's clothing for almost a year. There are no rules. It should be what your Dad wants and what you can handle. Now that you have seen the scope of the task, break it into sections and take this time to find out who would want some of her things as a reminder (girlfriends or sisters/inlaws) and what organization would benefit from receipt of these items. I find too often families forget a person's friends when the friends would love to own and be comforted by say a sweater she often wore.

Donna