Believe me, none of us are saying this to be mean, but your sister will probably *need* the vacation after something like this. (And if it were me I'd add a veeeeeeeeeeeeeeery long spa visit....)
Shortly before I met him, my husband had been laid off just before a major vacation. (The one that resulted in us meeting for the first time.) And when he spoke with a financial advisor, they told him to just go ahead and take it, for the same reason. Everything had already been paid up and reserved. What was canceling it going to help? Provided you can keep the rest of your life together, there's no harm in continuing with existing plans. (Granted, this was over 20 years ago...)
Does she have a friend or relative's house who she could leave her valuables/electronics/paperwork at? I'm sure there are ways that the rest of the house could be secured while she is out. The insurance company may even have suggestions. (Some are good about this, and some may even consider it a bonus that they don't have to pay for a hotel stay while her house isn't safe to occupy.) Pets can be taken to a kennel if need be.
I'm just saying it may be best to find ways to ease her mind while she's gone, rather than try to wiggle out of it.