Yes, it makes sense to move the Roth IRA into your mother's name. But there is probably no advantage to doing so ahead of time because it can be done when and if your father needs care. Just make sure someone has a durable power of attorney for your father to be able to take this step when and if the time comes.
The Roth IRA would fall within the approximately $137,000 (figure may be higher in some states) that the community spouse may retain and still get Medicaid coverage for the nursing home spouse. However, all but $2,000 of this money must be in the healthy spouse's name. So, if your father needs nursing home care, the funds will have to be transferred to your mother.
Again, this doesn't need to be done in advance. That is because the five-year lookback period for transfers of assets does not apply to transfers between spouses.