My 83 year old mom is taking care of her 83 year old physically ill husband and needs to be able to make medical decisions, contact his pension about his medical and death benefits, make a decision and act on possibly selling their home or securing a reverse mortgage, etc. He can no longer deal with any of these issues on his own. As his wife can she legally do these things or does he need to give her power of attorney to do these things?
Yes, Though she MAY be able to do some of the things you mention, she certainly will need both a durable and a medical power of attorney.
Do you parents have wills? Most lawyers include powers of attorney and other important documents when they draft a will.
All of this assumes your dad has the capacity to sign these documents. That is an issue you should discuss with a lawyer.
Mr. Land is correct. The biggest initial concern I read is, "he can no longer deal with any of these issues on his own." If he is no longer legally competent, he cannot execute a power of attorney. That would lead to the necessity to open a guardianship through the courts. This is a very difficult process. Powers of attorney eliminate that need, so it is crucial that if he is able, he execute these documents asap.