My sister-in-law wants to kick us out after being here 4 years. I have made over $16,000 of improvements to this property. She acts like it is hers but we have never seen a will or who the property actually belongs to, her or their deceased Mother..
We told her the dishwasher didn't work and she said go get another one. We did and took the cost out of the rent and installed it ourselves. Now she wants us to move.. how many days without a written agreement does she have to give us to get out?
We don't want to argue who got what... just want to know we have time to find another place and get out without being forced out fast.

What you do know is the home is not yours and you were renting. You sound like this is a verbal month to month rental without any written rental or lease agreement.

Without knowing where this is, this is a general rule, the rule for your exact location may vary.

They will have to give you a 30 day written notice to move out.

Where is this property located, eviction laws vary. Nothing verbal consisyutes the beginning of an eviction process. Waiting for location

In most states if there is no written lease agreement the owner must give you 30 days notice to move out, but it's shorter than that in some states.

You seem to be uncertain whether your sister-in-law is the actual owner of the property - so why have you been sending her checks for the past 4 years? You can check property deed records at the county clerk's office if you want to make sure she is the true owner. If the mother was the original owner and is now deceased the executor of her estate would have been responsible for distributing assets to the heirs, and retitling the property in accordance with the mother's will. If that didn't happen - the SIL would not now be the rightful owner and would not be able to evict you.