i want to contest my fathers house deed that has my step brothers name on it as the next owner.

Unfortunately, you will likely have an uphill battle voiding the deed unless you have a doctor's declaration that your father was incompetent at the time he signed the deed. Individuals with early to middle stage Alzheimer's usually have sufficient competency to sign a deed.

Assuming you have insufficient medical records to support your argument that your father was incompetent at the time he signed the deed, perhaps he suffered undue influence from your step-brother. This would be another way to void the deed. This must be proven by clear and strong evidence.