Legal Question in Wills and Trusts in Washington

Re: Do I have the right to this property

You can contest the will in probate, but without evidence of duress or fraud you would likely not succeed. As to prior to probate, you would need to prove her incompetent or subject to duress or fraud, probably in a guardianship proceeding, and that she was not competent to make the will. As to whether you would succeed, it would depend on what you have for evidence. Your testimony is likely to be discounted as you are an interested party, so evidence from independent sources will carry more weight.