Be careful: she is allowed to rent the property while she is still alive and use the proceeds to pay her bills.

She would have to sign the quit claim deed, but YOU could be seen as using undue influence... the scenario is this: If she is indigent except for this house life estate, then the government is likely picking up her nursing home expenses... which are repayable from her assets. While she cannot sell the home without the blessings of the remainder owners, she CAN rent it out and use that for her expenses... If YOU take over the house by quit claim, YOU might be expected to come up with the equivalent rental for the remainder of her lifetime to repay the government. Not a good result for your wish to gain early access to the asset.

If YOU take the house for purposes of selling it, then you take it as is... that is the result of "quit claim": NO WARRANTY. If she has no need for the asset value of the house to pay her bills, then YES, you might be able to get her to agree to sign a quit claim to you and your brother. But don't expect her to give you money to fix it up so you can get a bigger profit. Not happening if she is still sensate.