I need some hlep in Choosing a mutual fund for my Roth IRA?

Currently I am invested in a target date mutual fund for my Roth IRA. My wife is now starting her Roth IRA. Is it a good idea for her to get another target date fund from a different company or should we diversify more and get either a large cap or mid cap driven fund?

A target date mutual fund does the diversification for you. Unless you want to get more involved in the mechanics of portfolio balancing and using different funds to assemble a portfolio that you like, just stick to the target date funds.

A fund from a different company would be wise though. It's highly unlikely that anything would happen to either fund company, but as a general rule it's not good to have all your eggs in one basket.

You might learn more and in addition enjoy investing more by becoming more involved in the mutual fund selection process. Target date mutual funds are ok, but somewhat sterile, especially when incorporated into a Roth account. They also tend to be over allocated to U S stocks although some moreso than others.

One possibility would be Vanguard Global Equity Fund, only 37% U S holdings and also I might add a pretty good record of returns.

US World is a No Load MF Co. and the Gold, Precious Minerals Funds along with the China, India and Natural Resources are great funds to be in and to add positions to. All the above are non 12b-1 funds.

Personally, I am opposed to Target Date funds. These are intentionally conservative in their investment strategies, as they cannot tailor them to your specific needs.
Without knowing how old you are and what your current investment portfolio looks like I would just make a simply suggestion here. Its great you are investing in a Roth IRA, and I would suggest you avoid the Mutual Funds and focus more on ETFs and iShares. They operate like a Mutual Fund, so you will be just as diversified, but they trade like conventional stocks...so the value will increase as their demand increases. Their demand increases as their income/investment performances increase. Naturally you want to focus on certain sectors that your research suggests as strong areas of growth: such as the Energy Sector, Natural Resources (Especially Water), Emerging Market, IT, etc.
ETFs/iShares are relatively new, as they have been out since the early 90s, and have yielded some fantastic returns relative to Mutual Funds. I would also encourage you to have a portion of your Roth investment going into actual Bonds...NOT Bond Funds! Look into seeing if there are Municipal Bonds in your state that you can access. They offer a decent rate of return relative to the market and the interest income is exempt from federal and (generally) state taxes.

Hope this helped.