Do I need to add someone to the title on my home?

I am an attorney licensed to practice law in California.
First, at the very minimum you should have a financial/medical power of attorney document to address your financial/medical affairs if you are ever rendered incapacitated.  By way of example, if you become incapacitated without a durable power of attorney, then a conservatorship of the person and estate proceeding may occur.  This can be time consuming and expensive.  You should also have a last will and testament to distribute your assets to your beneficiaries upon your death.  This assumes that your probate estate is less than $150,000.   On the other hand, if you die without a will, then the State of California will create an "estate plan" for you.  This can be a disaster.
Second, generally speaking, a person can transfer a non-joint tenancy mobilehome registered with the Dept. of Housing and Community Development (HCD) without probate.   HCD has a form titled Certification For Transfer Without Probate form  (HCD 475.2) which your daughter can complete after your death.  This form will allow her to attach a copy of your last will and testament to the form and legally transfer the mobilehome to her without probate.  Mobilehomes are excluded from the "probate estate" under Cal. Prob. Code 13050. 
Third, adding your daughter as a joint tenant during your lifetime may trigger adverse gift and capital gain taxes.
Lastly, some mobilehome owners own both the mobilehome and the land underneath.  If you own the land underneath your mobilehome, then you would be wise to create a revocable living trust and fund the trust with the mobilehome and the land.  This technique will also avoid probate, too.
I hope this helped.