She should seriously consider it. A lasting power of attorney (LPA) ensures that if for any reason she becomes unable to deal with her finances or make decisions about her own welfare, people she trusts (her ‘attorneys’) can do so on her behalf.
Your mother can make a property and financial affairs LPA which gives the attorneys the power to deal with financial matters. She can also make a separate health and welfare LPA, covering decisions about healthcare and welfare.
In each case she will need to appoint one or more attorneys. Her attorney could be an adult family member, a professional adviser or anyone else she trusts absolutely and who has the experience and ability to manage her affairs. She can choose different attorneys for each of the LPAs if she wishes.
Your mother should also make a will while she has capacity to do so. Any will made once she starts to lose her mental capabilities could be invalid.