Okay so first of all regarding the enduring power of attorney.... As it is now active, YOU have authority over ALL of his assets.... the fact that your mum is on the title or has an equitable interest does not override your authority as his EPOA.... Meaning you can deal with his assets as you see fit (acting in his best interests).... Assuming mum has not moved herself back in already?..... You can enter the place & change locks if you wish.... I can't give an opinion with the police involvement cause I don't know the circumstances, but failing to take the advice of a cop on a domestic dispute is hardly likely to get you in trouble so I wouldn't be acting to quickly in removing furniture or vehicles if you don't think it's in dads best interests (unless it's to family members who want it)
The situation with the will is that the entire estate (house included) is to be split equally between siblings (assuming)... But mum has an equitable interest in the place via family law & also right of survivorship (joint tenancy)...
I am not a lawyer & you will definitely need some solid professional legal opinion on the best course of action if you want to prevent mum from taking possession of the house after dad passes...
First off you want to know if your mums right of survivorship overrides your dads will (assuming it's valid will), taking into account that they were separated & estranged for several years prior.... Perhaps you could post that question in the wills & estate forum of this page.... Hopefully you will get an opinion & perhaps an invitation for an interview to discuss it in more detail..
If your relationship with mum is reasonably amicable, she may include you siblings in a future will (which is what would normally of happened if they hadn't separated).
If she challenges the will at probate any legal costs will come out of the estate, so I guess there would be some incentive to reach an agreement rather than take it to court