Wellesley Income is a fund that everybody thinks of fondly. It does have a great long term record and the expenses are mighty low for a managed fund. However, it is not as diversified as some would like. For example, it only contains 64 different stocks.
For this reason, some people mix Wellesley with the Target Retirement Income fund which has thousands of stocks and a wider variety of bonds. I'm just throwing this out for consideration.
I think 500 a month is a reasonable amount to withdraw - that's right at 4%.
Another thing to consider is purchasing a single premium immediate annuity (SPIA). By doing that, you would essentially be buying a specific income for life. At her age, she might get more than $500 a month, but if she dies before the whole $150k is spent, you don't get any money back. Well, there are ways to get money back, but it would involve her getting less each month than if she does not buy that option.
Do not consider any other kind of annuity, just a SPIA. You can get estimates off the internet, but I don't know which sites are reliable and which are not so I won't suggest one.