This dog has been let down badly by the person who supposedly cares for her.
They should have made sure she was well trained, happy to relax and ignore noises, not anxious and easily over-aroused.
She may well be being a PITA to you, but it is because she's struggling to cope, not just with missing your sister but her entirely world has changed, she doesn't know why, or that it's only temporary.
Don't let her outside unsupervised.
Take her out (ideally on a long line clipped to a harness if you have either, so you can bring her in without chasing or shouting), armed with high value treats.
Pair every noise with a treat, make like this is the best thing on earth, don't wait to see if she can shut up or not bark, you're trying to classically condition her that noises = treats, to change her underlying emotions.
This can work quite quickly if you're consistent with it... but it will be intense for a few days.
When she looks happy about noises, you can start to drop the rate of reinforcement somewhat so she does a sit or looks up at you for some of the treats and some are still 'free'.
Really, this is something your sister should have done a long time ago, but it's you and your neighbours and the dog who are suffering right now and this is the only way to address it that doesn't involve unpleasant aversives and a high risk of 'fall-out', ie unwanted side effects.