We enjoyed going to estate and tag sales. One company locally handled the majority of the sales. Usually had them for 3 days at the home, reduced prices 3rd day. I don't know what they did with the unsold items.
If we went early the first day, there was a line, and the sale company would only allow a certain number of people in. Later in the day, they weren't so strict.
You'll have to decide what your goal is-I saw you mentioned paying for your Mom's care, so you'll probably want to get the most out of her collection as you can. Check any time limits. Usually Medicare pays for some long-term care, but I think she'd have to be admitted from a hospital. It's been almost 10 years since we had to help someone and I imagine things have changed. Anyway, if you have limited time, that'll probably influence how you sell the collection and how much it'll sell for. Avoid telling your buyers you have to hurry. They'll try to talk you down. As for price, you can come down, but if you try to raise a price, you'll probably lose the sale.
If you are aiming to clear the house to sell it, you'd probably want to approach selling a different way, maybe an auction. Even if the auctioneer takes a percentage, your main goal, clearing the house will be accomplished.
I wish you good luck. My husband and I collected for over 40 years. He passed away in 2017. I took time to sort and last year rented a booth in a vintage store to downsize. That is working for me, but it might not work for your family. Good luck to your Mom. I bet she loved collecting her things, and got joy and pleasure from her activity. For a lot of things, we are caretakers, or curators. At some point, we have to bow out and let the next generation care for the treasures.