No doubt your aunt feels the loss of her husband very deeply, and I suspect she is trying to relieve her grief's pain by seeking this person's advice. However, she is going about it the wrong way, and I hope you will discourage her from pursuing this path any further.
Why do I say this? One reason is because this person's promises may well be false, and your aunt will only be deceiving herself and throwing her money away. Self-proclaimed psychics are often very good at uncovering what people hope to experience -- and then making it seem like it actually happened, when in fact it didn't. You are wise to be skeptical of this person's claims.
But there is a much more serious reason why the Bible tells us to avoid anyone who claims to be able to contact the dead or do similar occult tasks. It is this: Such attempts may bring us into contact with demonic spiritual forces that are opposed to God. This is why the Bible says, "Let no one be found among you ... who is a medium or spiritist who consults the dead" (Deuteronomy 18:10-11). Your aunt should take this very warning seriously, for Satan's primary goal is to deceive us and turn us away from God.
Instead, I urge you to point your aunt to Jesus Christ. Only He can give her God's peace, and only He can give her hope for the future. And if you have never faced your own need of Christ, open your heart and life to Him today.