Welcome to the forum!:)
What a blow for you, both parents with Parkinson's!:(
I had similar problems with urge incontinence a few years ago and often had accidents on the way to the toilet. I had no choice but to wear an incontinence pad (by the way, there are some very discreet incontinence products available) otherwise I would not of been able to go anywhere. What helped me was adjusting the strength of Levadopa (madapar, sinemet)and taking it more frequently. I was on the same daily dosage but smaller doses taken more frequently. Within days my bladder control returned. Below is a link to a booklet which i think you will find useful. You can print it off or phone the helpline 08088000303 and request a copy of the booklet to be sent to you.http://www.parkinsons.org.uk/pdf/B060_bladderandbowels.pdf
There are drugs that can help urge incontinence and this can be discussed with your mum's PDN/Neuro. I also tried Madapar and it had no control over my PD symptoms. Is your mum on any other medication besides Madapar? I ask this because I have also had problems with hallucinations in the past.